As I posted way back when it was released, I've had zero problem not only getting all the popular mods to run (SKSE, SkyUI, Unofficial Patches, darker nights / dungeons, Relighting Skyrim, etc) but doing so 100% offline (from a local backup) without any client, mod manager or online connection, no different to Oblivion. The "Current GOG Anniversary Edition build 2.2.2" version of SKSE was released same day Skyrim was on GOG. Most mods aren't tied to specific game versions, you literally just drop them in \Data as with Oblivion and Morrowind. Some that are will break (as they do on Steam after an update) but it's far more like 5% don't work and 95% of mods do.

I suspect Ancient-Red-Dragon's "99% of mods are broken for GOG-Skyrim" skewed outlook problem is caused by Mod Packs, ie, where someone takes 500 different mods and bundles them into one. If 1/20 mods don't work but all you do is use mod packs containing more than 20 mods, then statistically speaking something is likely to be broken in every mod pack and it would appear "nothing works" but in reality 19/20 mods do work if you install them individually. Mod packs have always been notoriously fragile in general anyway when it comes to "something broke my game but since I installed 500x of them at once, I don't know which and find it impossible to troubleshoot the same way I could installing & testing them individually".

All the "quality of life" mods I want though run just fine, and in no way shape or form is demanding Steam DRM be put back in into the same GOG version that it was removed from "doing the right thing". The whole point of the GOG version (and why it's different) is that all the Creation Club content actually works offline. That involved going through the code undoing a lot of online CC "hooks" in addition to all the Steamworks DRM and Steam Workshop stuff. DRM-Free Skyrim is never ever going to be "exactly the same" as the DRM'd walled-garden one, nor do most of us of who want a DRM-Free non walled-garden version want that...