I personally am quite fond of the grid pattern gamelist instead of the gamelist like it is currently. Emulationstation had plans for a grid pattern but never quite got to it before real life got in the way.
A minimalist design is the way it should be in my opinion. Kodi has done a very good job with their layouts and theming options, game frontends are a bit behind on that front. There is also this one that you might be able to adapt:
https://github.com/RetroPie/RetroPie-Setup/issues/1071
You could also look into retrofe
I’m not sure your level of coding experience or if it would just be easier for you to find something that’s already built and just make a theme for it, but I like your preliminary ideas :)