Clean install of Windows 10, fresh install of New Vegas on GOG Galaxy. I cleared all the save files/game data. Went into app data to clear that as well. Tried loading only the base add-ons to no avail. Have tried using some anti-crash and performance enhancers from NexusMods but they didn't really work as I had about 5fps after loading in.

Just trying to play the game like after the first time I bought it :'( Please help!

Which GPU? I had the same problem with an AMD GPU until just now. The latest Adrenalin driver 24.6.1 fixes the problem for me.