@SuperFromND Alright, I'll try it. Thanks again!

Oh, one more quick thing (adding this as a separate reply so that those watching this thread get a notification for this):

I've decided it would be wise to update the original post at the top of this thread to reflect the current status of IKEMEN GO on the Pi 4, since it's almost entirely out-of-date. I've archived the original post on Wayback and will be including a link to this archive as a footer note. It should save newcomers some confused scrolling around to get this up and running. :)

EDIT: The post has been updated! It now includes a tutorial on how to install IKEMEN, configuration, and the like, which should be SUPER useful in the long run for newcomers.

retropie supports neither mugen nor the switch, so...

Wine only emulates the operating system, the PC Diablo binaries are still x86 so will never run on a Pi. If you want to play Diablo, there is a PSX port.

Yes, N64 emulation is crap for many games, the Pi is weak and emulation is not that good anyway. A few games work well such as F-Zero X.

There are apparently some improvements to N64 emulators coming so maybe the situation will get better in the next few months or year.