Batocera on spare machine you have running for a really easy nearly turn key experience. Its also pretty good at handling controllers and has an ok wiki Has kodi built in which you cna use jellyfin plugins (i dont like those though) I dont think it does multi user which may not work for parental controls (big beleiver in talking to your kids solving most issues) And no RomM plugin last time i checked maybe has it now.
Little bit more manual but with nearly the same front end ES-DE. Maybe with emudeck to make it a bit easier to manage. i have this on bazite with steam big picture and ES-DE as a non steam game. Theres also steam rom manager but i havent used that.
For ease of use and setup and wife kid friendly and just less life stress use batocera. Boot it from an external usb to try it out. If you find it gets some use you could install ES-DE on the main os and manually manange. Or just dual boot forever depends on your tinkering appitite.
Yes yes you csn.
The old may was we would run these direct like an app on the pi.
People then came up with containers and isolated things a bit made them easy to share and configure. - dockers
Have a look for people with blogs about all the software they are running on their pi plenty of info on how.
Pi isnt the best at jellyfin server as it isnt the best at transcoding files but for direct playing without having to convert the format its enough.