If you like my work please consider endorsing!

I decided to apply my Divinity: Original Sin mod to BG3.  Now out of beta and officially 2.0 released!
If you want to take FULL advantage then I'd recommend starting a new game, but I can personally confirm it does at least partially work with in-progress saves.
The thing to keep in mind is that any already cached containers or vendors in your save will retain their previous loot rolls.  You'd have to rest or otherwise reset a vendor for them to use the new rolls.  For containers, you'd have to visit a completely new area you've never visited before for the mod to affect those.
Basically, this mod affects NEW loot rolls; if the loot roll is stored in your save then that roll will persist with or without my mod and containers roll for their contents when the area they are in is first loaded, NOT when you open them.

So, what did I do?
    TL;DR = With this mod you'll always get (one of) the best possible loot results you could have received in the unmodded game and will not be penalized for looting as a lower level character
1) Removed all references to the "Empty" loot table that I could without removing things which are hard-coded to be empty.  (By popular demand, there is an addon to override this tho)
2) Maximized all loot rolls such that merchants, drops, and containers will ALWAYS have the most items they could possibly have rolled in an unmodded game.
3) Removed most level restrictions on loot so plate armor *ought* to be available from lvl 1 if you have the gold (or luck) for it, but at the same time I also kept lower lvl items (which were coded to be removed as your party leveled up) still available at merchants so you can have access to ALL the wares possible regardless of level. (By popular demand, there is an addon to revert this change tho)
4) Where necessary; I kept lower tier items in the lists of possible drops which otherwise could have seen such items disappear from the game entirely, just with lower drop chances than higher tier items - however I otherwise kept the devs default for WHAT could be in a loot list.
5) Tore out the vast majority of junk items (yes, including rotten food) where they could otherwise take the place of more valuable loot.  The only exception to this rule is if it was a choice between a junk item and NOTHING, then I kept the junk item.  The same goes for any places in the code where eg a non-magic item could take the place of a magic item or a lesser magic item take the place of a greater one.
6) Also fixes a few bugs and typos the game devs haven't found yet, including some *VERY* minor performance optimizations - those will only save your PC like a handful of nanoseconds worth of processing time, but I can't not fix those when I see them.

I didn't add any new items (well, not in the base versions anyway) my goal as always is just to make high/unlikely rolls the default behavior such that you could always replicate the results with enough save scumming in an unmodded game.

To install/uninstall a PAK version I'd recommend a mod manager like LaughingLeader's
- Just always load BetterLoot BEFORE any other mod, and load BetterLoot100 anywhere AFTER the main download!

To install a LOOSE FILE version just drop the PUBLIC folder into your game's Data folder so the file structure is as follows:
C:\Program Files (x86)\Steam\steamapps\common\Baldurs Gate 3\Data\Public\Shared\Stats\Generated\TreasureTable.txt

To uninstall just delete that folder.

Oh yes, and disclaimer; the launcher will complain about the loose file format with a "Mismatched Data" error, but that is safe to ignore.

Any other LOOSE FILE mod which edits TreasureTable.txt is going to be incompatible with my LOOSE FILE versions without a manual merge.
With my current understanding of this game engine - loose files ought to be loading before pak mods which is actually exactly how this mod should be loaded - first.  That means this mod SHOULD be compatible with any pak mods even those which edit TreasureTable.txt assuming they are done right.
Worst case you'd just see less and less effect from BetterLoot as more and more of its changes get overwritten.

If you want to examine exactly what changes I made I'll include the original unedited files as an optional download and you can compare them with the naked eye or a program like WinMerge

For those interested here is a complete breakdown of what can be spawned when the game tries to make a call to the EMPTY table with the 100 addon installed:
5 chances to spawn a Gold Coin
2 chances to spawn a Half-Eaten Apple (1 Camp Food)
1 chance to spawn some Cheap Alcohol (1 Camp Food)
1 chance to spawn a Fish Head (1 Camp Food)
1 chance to spawn a Candle
===================
10 total chance pool, so 1/10 = 10% chance

My "Fill ALL" addon fills hard-coded to be empty containers by overwriting the Empty table to instead return 1g worth of *something* but if you want more than that, then what you might be looking for is a mod like No Empty Chests.  Which does the same thing my addon does; overwrite the Empty table, but goes further than just 1g... while also re-introducing junk items.  There is no solution that EVERYONE would like to this problem, so if none of these exactly fit your preference then by all means break open my "Fill ALL" addon and edit it to your exact specifications - that addon is super simple and easy to edit.
(If you want to edit pak files then you first need to unpack them; I use Norbyte's lslib)

NEC is fine to use with the BetterLoot base mod, but would conflict with the "Fill ALL" addon since they are doing the exact same thing.