Don't shoot engaged things. And swapping for dagger or rapier and shocking grasping enemies is always an option.

Oh thanks for the tip I didn't know I could do that and yeah I forgot about touch attacks...

Is touch of fatigue cantrip also a dps increase over just poking things?

Depends on enemy AC. If your chances to hit would drop to nat 20 with that -2 it's totallty not worth it. Otherwise - yes, kinda. Dex scion generally just wants the agile pick and everything will be sunshine and roses. I usually shoot stuff once or twice and then go tank melee with fighting defensively on. Doesn't matter if you hit or not - just need to be there. Pretty much same stuff as valerie. Let your backline do the damage. And once you get to the agile pick you can start thinking about damage.
Wonky start is very much the reason I'd never use dex scion on unfair.

Slayer

Race: Tiefling(Motherless)
Alignment: LG*
*We are kinda fine with whatever lawful, but it’s far more beneficial for deliverer. And you’ll want absolver cloak anyways.

Stats:
Str: 18 > 22
Dex: 14
Con: 15 > 16@20
Int: 12
Wis: 14
Cha: 7

Final Build: Fighter(Aldori Defender) 2/Slayer(Deliverer) 12/Bard(Archaeologist) 2/Dragon Disciple 4

Main skills: Persuasion (Max), Perception (Max), Mobility 3. Knowledge(Arcana) 5
Suggested secondary skills: Trickery(Max)

Detailed leveling breakdown:
Lvl 1: Slayer - Dodge // Irori
Lvl 2: Slayer
Lvl 3: Fighter - Crane Style // Shield Bash
Lvl 4: Slayer
Lvl 5: Slayer - Two-Weapon Fighting(+2 dex item) // Combat Trick > Crane Wing
Lvl 6: Slayer
Lvl 7: Slayer - Outflank // Menacing > Intimidating Prowess
Lvl 8: Slayer
Lvl 9: Slayer - Improved Two-Weapon Fighting(+4 Dex item)* // Menacing > Shatter Defenses
Lvl 10: Slayer
Lvl 11: Slayer - Shield Master
Lvl 12: Bard
Lvl 13: Bard - Greater Two-Weapon Fighting(+6 Dex item)* // Crippling Strikes
Lvl 14: Dragon Disciple
Lvl 15: Dragon Disciple - Double Slice // Blindfight
Lvl 16: Dragon Disciple
Lvl 17: Dragon Disciple - Crane Riposte
Lvl 18: Slayer
Lvl 19: Slayer - Accomplished Sneak Attacker // Menacing > Dreadful Carnage
Lvl 20: Fighter - Bashing Finish
*get accomplished if you didn't find +4 item yet. Swap double slice and improved then, take double slice at 19.

Spells: Remove fear, Cure Light wounds, Vanish, Mirror Image, Glitterdust, Sense Vitals

Gear: Best armor you can find. Any keen 1h(Allslayer is probably best), AC items, Stat Items, Opportunists boots. Lesser extend rod for Mirror Images

With haste you can get up to 10 attacks per round with 7d6 sneak attached. Pretty solid. Can reach 70AC with buffs.

Self-sustainable mirror image.

Doesn't dazzle for himself, although does have enough for single-target intimidation should you need it and dreadful carnage once you get the ball rolling.

Solid front-liner. Don’t think you can squeeze much more out of the class. Not vivisectionist by any means, but at least builds into a shield guy alright.

Would you want to update your off-tank nok-nok build or mad-dog trip bite-barbarian build in any way now that there is slayer instead of freebooter?

Also looking quickly specifically into the 1level slayer dip on sneak mages but on sorcerer there seems no point really as sorc spell progression is already 1 level slower than wizard.And also on wizards I think it is questionable. Slayer brings martial proficiency which is good for eldritch knight build but dc casters don't care about eldritch knight and getting extra spell options through new arcana for an extra level 9 spell seems better.
Even 1 level dip in fighter for martial and an extra combat feat seems better on eldrich knight builds or just take the martial feat on your main class to avoid falling behind even more on spell level progression.

Non-nok - probably not. I still kinda like all the AB booter gives to the party. Not being selfish is kinda the selling point, especially give he loses so d2 on sheildsneak attacks. Also I am of the belief deliverer is the way for the slayer. As to AK builds... well I did find a very interesting chainmail on my short session with endless dungeon(went to level 29 and ripped cause I'm a moron)... Now I just need to replay the whole damn game to see if it can be found reliably somewhere, so that'd make armored sorc/ek's life more exciting with a new shiny slayer dip. As to total min/max cases... you;d go monk invalidating the gains from irori pick, so that's a no-no.
That being said, I will go through my builds and see if it's benefitial somewhere when I have the time. Kinda trying to balance working on this and actual playing the game.

Would you consider the Kinetic Knight Valerie build stronger than the what I assume is lore friendly build?
Especially early-mid game.

Depends on a difficulty. For unfair it's not much of a competition: standard build wins out if only on the merits of ramping the AC faster(especially cause I'd go crane wing/riposte instead of armor feats for unfair. I try to not abuse the bugs on standard builds). KK valerie is bit more of a damage dealer with drawbacks that you could expect associated with it.

big worm doesn't actually have a lot of HP. So murdering it with shocking grasps shouldn't be too hard. And centipedes don't do much. Pretty much the trick is focus-fire, not some fancy tactics.

After a few hours of trying to not end up with either multiple dead party member or being de-buffed to something like 1 Dex I gave up. I almost couldn't hit it at all. Even with Arcane accuracy. If I did then the attack did something along the lines of 10 extra damage only on crits it ever got up to 30+.

But funny enough I now read that there is an AC stacking bug for enemies with the newest patch. Though I'm not sure if the worm was affected by it and I think Dex Scion attacks are touch anyways?

I will give it one more shot to play on hard before I need to realize that I'm not good enough for that yet. Even though challenging did feel a bit too easy. I did learn some stuff about positioning though so that's nice at least.

You mentioned it's okay to go monk whenever in the first 9 levels in your Sylvan Sorc build and I feel like I would profit more from a stronger pet and stinking cloud earlier. Would be taking it after getting stinking cloud truly okay? I never really felt like my Sorc was focused anyways and didn't really need the AC.

Also one last question: Do Saint and Trip Vivi have a stronger early game than Dex Scion?

Depends on what you want. If we are talking tankiness - no, not at all.
Generally earlygame is pretty scummy on unfair and amounts to hiring a sylvan sorc halfling with mage armor and grease. Then you proceed to ditch everyone from the party to level faster with you, valerie and sylvan sorc. Will take quite a bit of reloads, but hey, it's not like there are many options when you get one-shotted by anything.
Also visit Old sycamore before tomb. It has quite a bit of stuff to kill that will vanish when kobold/mite conflict starts.
Melee starts are hard. Str ones have meh AC and Dex ones have no damage.

Oh wow, thanks for the tips. I didn't know that stuff despawns either. I always did tomb before.

Sorry for questioning again but do you think it's okay to take monk at around lvl 7 or 8 on the sylvan sorc or should I just stick to the build for hard?

I prefer taking it at 9 along with crane wing. No real point doing it earlier as it only causes you getting stinking cloud later.

Thank you so so much for all your help so far. I really can't express how much it means to me.