Overall it seems like Larian made an improved version of 5e. I almost want a PHB based on these rules. It's like an Advanced 5e.There's definitely some things that wouldn't transfer to the table top as well like handling 4 boons and buffs to every roll.
I really like the camping supply cost to long rests and the weapon special abilities recharged on short rests.
I don't really play 5e much anymore but the notion of special weapon maneuvers and making shoving/jumping into bonus actions are both things I'd consider porting into it when I do pick it up again. The buff to True Strike would probably be in the cards as well.
Definitely not, but not because they're bad changes. Larian made a goddamned amazing cRPG. BUT, a good cRPG a TTRPG does not make.
There's a big movement among DM's to make gameplay crunchier, less forgiving, and more mentally engaging. Larians changes with camping supplies and weapon abilities are both examples of this kind of design philosophy.
However, the vast majority of TTRPG players these days are not either veterans or DMs, and a decent portion of them aren't looking for crunchy gameplay. They want ease of use and fun.
5e isn't perfect, but it is massively more approachable than 3.5e or many other systems. Adding new mechanics like "Hey man, I know that you're a wizard and like casting spells is the whole reason you picked this class, but you didn't loot that fish off a dead goblin earlier, so sucks to be you" is just going piss off players.
At my table it's a simple "Are you in a safe place? Cool then you can long rest". No extra mechanixs, just a simple "Is your character safe to totally relax for 8 hours".
In both systems we're making our players think twice about using their abilities. However, Larian's system would encourage gameplay that's not engaging or rewarding, while mine just encourages mindfullness about where you sleep.
I highly encourage watching Matt Colvilles video on how game system's rewards are indicative of the style of gameplay they are desiring because it works both ways.
Regarding mechanics, I'm totally fine with 5e. To each their own, I guess, because I see BG3 implementation as totally bogus. :) Which does not prevent me from loving that game greatly, it's just "inspired by dnd", to me, mechanics-wise.
Regarding lore, now, certainly I will reuse it! I'm all in the Forgotten Realms, having read countless novels within it, read all 5e adventures (despite never playing them - I take them as current events context to play my own campaigns), and many previous edition adventures, I'm always happy to get new official lore to make my version of the realms richer. :)
And an other aspect on which there will be a before and an after BG3, for me : roleplaying goblins. My goblins are usually "evil dumb", somewhat not very far from kobolds, if a bit more petty and snarky. I totally love the full blown insufferable assholes BG3 made of them. I will definitely copy that.
I've lifted the supply mechanic entirely. I built a system for my group which incentivizes foraging and cooking, but it was a little hazy on what constitutes one person's daily ration.
It's always been a bit of logistical haggling come the end of the day, breaking everything down to supplies makes it much easier. As opposed to a flat 40, I made a requirement per person and pack animal that they must meet for a full long-rest. My group loves recruiting, gotta make them work for it a little.
The second is how they handle Inspiration. I've always hated this mechanic, but I've since implemented it as a second chance reroll like BG3. It works much better and incentivizes the players to use it and not hoard it.
So far the player feedback has been positive, I don't know that mine would care for the weapon skills, but I'll keep it in mind.