I bought this game almost a decade ago and no matter what modern OS I try to run on it, it simply refuses to run. I get no further than the splash screen and that is it.

I even tried to use the Union patch, but even that failed to run.

I don't know what Union patch is, but the System Pack should help.
Otherwise I would suggest to look at pcgamingwiki.com how to get the game running under modern systems.

I have a laptop with 2 videocards (Intel HD something + Nvidia) and Windows 10.
Gothic 1 hung up on a startup (as a small black screen).
Solution from the last post in this thread fixed this issue:
https://www.gog.com/forum/gothic_series/gothic_1_working_on_windows_10

I managed to run the game, but after applying mods and patches, it refuses to launch or function properly.

I decided to purchase the Gothic Universe bundle on Steam since that game works seamlessly out of the box.