My advice would be to pick the GAME first, then, depending the type of the game, that decides your device. I personally own a Miyoo Mini (not the + model) and it is a very cool albeit tiny device, I can’t see myself doing precision controls on it, such as street fighter. And games like Shining Force are just a little bit too small for the screen, I’m currently running Chrono Trigger and Fire Emblem on it though, which I think is perfect and “casual” enough for its size.
I find the Steam Deck the best choice for when I want to run Gamecube or N64 Emulation, owning the steam deck has allowed me to cut the Nintendo Switch Online Expansion because why pay for a subscription of N64 games when you can play them on the Steam deck? :)
Lastly, you actually have more options! EmuDeck recently came out with cloud-based save states. Your Steam Deck and Miyoo Mini + both are wifi enabled and could take advantage of that!
I have a slightly different setup personally! I am actually happily running a Windows Pro server.
For my Drivepool redundant storage, I am utilizing a cool tool I came across years ago called https://stablebit.com/DrivePool and I’ve been really happy with it!
I RDP into my server a lot for coding projects, and misc things, almost like a secondary computer. Additionally, I enjoy being able to Steam stream several games from it to my phone or laptop on the go. A surprising number of games are playable in this fashion.
Outside of that, I do selfhost multiple serices: