Snow Bros. (iPhone 11, Delta, GameSir T4 Pro)
Getting retro game emulators to work smoothly on iOS was challenging for a long time. You had to sideload app files (IPAs) by signing them yourself via AltStore before loading any ROM files for old Nintendo or other classic games.
However, things have recently changed with the official release of the Delta emulator on the App Store. Now, I can simply install the app and load the games from Files. I paired my device with a Gamesir T4 Pro Bluetooth controller today -- having an absolute blast reliving classics from yesteryear.