

You have to delete the two Intro-Videos in the Gamefiles under /vid. eversim.avi and intro.avi

Proton-6.5-GE-2 GloriousEggroll
Had to install all codecs but intro video was still not playing. At least with it you can skip it.
protontricks 1379930 allcodecs
But I guess the only necessery component was directshow because with it you could skip the intro video as mentioned here: https://github.com/ValveSoftware/Proton/issues/3951#issuecomment-683907790
Would be nice if the developers of gps 2020 could add a flag to skip that shitty intro.

Tried Everything
I tried almost all versions of proton with disponibility in steam, and all result in a black screen, and just that (some others didn't start the game, just showed me an error (VERSIONS 3.19 and below)). And just to say, I tried to proton GE (v. 6.1).