You sound like you've explored at least a few options in this space. Have you looked at https://agones.dev/ ?
This all probably speaks to my odd prioritization: I want to understand and use. I’ve had to step back and realize part of the fun I have in pursuing these projects is the research.
Bare metal is the only actually good option, but you often have to do a lot yourself. Multiplay did offer it last time I looked, but I don’t know what’s going on with them now.