I installed Ignited via SideStore. No Jailbreaking necessary. Not computer tether. SideStore can renew the side loaded emulator every 7 days when on WiFi. The iPhone is perfect for DS emulation with a stylus.
(Ignited is a fork of Delta with more options, and SideStore is a fork of AltStore, with no computer tether needed)
Never heard of the sidestore, but it seems so cool! This gets me closer to switching to iPhones than any of Apple's events do. If the sidestore has a real file manager and local music player, and possibly even Firefox+uBlock origin, I would seriously consider switching to iPhone.
About Firefox, all browsers on iOS have to use Safari engine so they are basically just a Safari skin so I don't know if you can use uBO but probably not.