I've selected some gaming benchmarks from games I know how they perform now: Link
So for consideration:
GTX 1080 (Desktop) is the performance I have right now. I want to keep this performance (±15% is ok)
this means everything above this performance is wonderful and doesn't need the eGPU setup
everything below will tend to have the eGPU setup. I might argue that a GTX 2070 max-q might suffice for the first year, so I've got time to find an appropriate eGPU setup :D But it could also hurt my little gamer heart.
Also, I wrote that I have and want 144Hz screen. This does not mean I must play on 144Hz on AAA games. I tend to have a solid >60 FPS (take 80) with 2560x1440. Battlefield V in this selection would be the game. Also take away like 20% FPS because it is not optimized for WINE.