Just wondering whether BG3, in its current state, does any of these obnoxious things with its quests (particularly sidequests). Does the game do any of the following:
* Push you into starting a quest with a conversation you don't initiate.
* Have a time limit on any quest.
* Have a character leave if you ignore their quest for too long.
* Bother you with quests when you're just trying to get stuff done in town (like buying/selling items or managing your inventory, including walking through town to accomplish such things).

(These sorts of things are, IIRC, what caused me to stop playing BG2. Yes, it was this sort of thing, not the awful real-time-with-pause battle system that made me quit. (For BG1, it was different; it was the game having me fight an enemy that cast Improved Invisibility when my party was still level 1; at that level, there is *no* way to counter that, so that just wasn't at all fair.))

How about "have characters start arbitrary duels to the death if they are in your party at the same time"?
It kind of sucked.

OK, we can add this to the list.

(On the other hand, I am OK with a character refusing to join if a certain other character is in the party.)

It has most of those. Some conversations are cutscenes that trigger when you reach a certain spot, and those may move the quest forward or start a new quest. I don't really know if you are actually in a race against time, but the main plot does suggest so. If a countdown is really implemented in the game, that I do not know. But you are supposed to have a time bomb in your head (or something like that), and that's the main quest for the game.

No companion NPC abandoned me for not doing their quest, but it's too early to tell. I played the game for 8 hours irl, but I only rested once and only one day went by in game. Yes, I'm a slow player.

I'm actually hoping to find some kind of town where to sell all my loot, because my inventory is full. I think I'm not far from it, but I'm not there yet. Most of the interactions between characters happen in camp, similar to Dragon Age. I was not interrupted so far by companions to hurry and do something, even if I lingered quite a while exploring the region.

I'm sorry if I couldn't answer all your question, I still have a lot of game to play. Hope it helps. Not all characters like each other (some do), but they didn't draw swords yet. I enjoy a good party banter though.

I haven't played the game for as long as most people but so far it seems everyone in my party dislikes each other.

Party banter is well and good when it's initiated by the player (like in Dragon Quest games starting from Dragon Quest 7, and from what I hear some of the Tales of games have skits in them). (With that said, there should be a way to back out of it; being unable to do so was annoying in the Final Fantasy 3 remake, which has the ability to talk to a temporary character (as also seen in SaGa 2 and possibly SaGa 3).)

What I don't like is when I'm trying to do something else and am interrupted by party banter, which is what tended to happen in BG2.

nothing of what you're complaining of is anywhere near that bad to be a showstopper in BG2
actual timed quests (and consequently chars leaving if you don't do it in time) are quite few and far between
and while the quests initiated without manually starting the convo aren't timed, then what's the feckin problem then?

>it was the game having me fight an enemy that cast Improved Invisibility when my party was still level 1; at that level, there is *no* way to counter that

just proves you're doing something wrong. or just a troll. BG1 is a really low-level game and the only problem players have is really early in the game but not fighting tough mages of course - mostly wild life (a bear can be a handful early on especially for a newbie to Infinity games). in such cases athletic approach (or reversely, scouting ahead) is the saving grace.

not arbitrary tho

I just went to an early game town (still at level 1 because the game is way too stingy with experience), started a side quest, and at the end the quest giver attacked me and used that spell.

BG1 is low-level by design and yes stingy with XP but that's a problem mostly felt early on. The further you get the punier the opposition would seem.
as for your trouble.. well that's your "open world" (or the illusion of such) for you. care to tell what the quest was?

push you = yes
have a time limit = sort of
characters leave = temp yes i.e, they go do something on their own
bother you = yes... mostly cuts jumping in because you character happened to walk pass some random rock
p.s, selling items is a major pain in the ass... click, click, click = one item sold and only 200 more to go :{

most assassins were lame ass. don't recall having problems worth remembering with that one in particular. taking him 1 on 1 tho could pose a problem. just pick up the merry couple of xzar and montaron. that's what they are there for.

I didn't have major problems with him neither. Maybe a couple of load games, but nothing too serious. But I was thinking maybe that was the encounter the OP was refering to. Ok, I played BG3 a little more now and I can confirm this is no longer the case. Companions still have things to say outside of your camp while adventuring, but they just get an exclamation mark on top of their heads, indicating they have something to say. They no longer initiate dialogue, it is you who have to, and can do it anytime you feel comfortable about it.

thats not always true mate... if you try to do something they may jump in to stop you... [trying not to give plot twists away here] the only way around them blocking you is to park them back at camp