Once the DLC unlocker is used where does the dlc appear? It shows up on the start screen under dlc but not in the game, i thought it appears in the malbox?

Yeah, this is now almost comically sad. I've been asking on the Pathea discord forever now, and if you believe Pathea, they apparently did submit the DLC content to Team17 with this update to be published to GOG. That obviously didn't make this update.

After this latest update went live, I asked them again about it and I got the reply: But realistically, if Team17 can't even be bothered to update the Patch Notes correctly so they display in GOG Galaxy, what are the chances they'll be bothered to fix this? It's kindof sad...Consoles really did get DLC before GOG, and at this point I believe GOG may end up being the only platform to NOT get DLC.

If Team17 doesn't have the resources or capabilities to actually support a given platform they shouldn't publish there. Way back before the Aug 2019 update, they should have just shut it down and offered Steam Keys.

Using the Unity mod menu (Ctrl+F10) and selecting which DLC to enable there.
The mail only gets delivered when you enter the "World" map. i.e. you need to enter your house and exit your house.

Yeah it looks like the mod isn't working, it says the dlc is unlocked but it never appears in game.
Nevermind found out what was missing

Aren't the DLCs exclusive to Steam? Sometimes Steam does that - cut them a deal (lower the cut Steam gets from sales) by making certain DLCs only exclusive to them so that people won't buy the game elsewhere. They've done that with other games.

Right and what's the point in this case?

I actually bought the game again just to see what the difference was, and, boy, do I feel like a moron.

It's because of situations like this that I still don't like DLC. Companies make them for extra profit then make a mess. Just ethically create ur game and release it, then work on a full extension and release it, not a bunch of small paid extras.

GOG had been fighting a lot of issues on game market over the years. DLC, DRM, monopoly... It's not GOG blame that this publisher is grabbing money here without providing proper support. It'd be tough for GOG to supervise publishing of different content on different stores, sadly it's us who must be careful and properly verify if each game is being sold in full.

For the other direction, there are tons of H games on Steam that are censored and users are banned when they warn about *official* patch being available, while these patches are published directly on GOG.