Bandcamp or 7Digital for music

There are also fan run repositories of games hosted through Myrient and the Internet Archive if you just want some specific titles or need a particular version for patching.

For emulation, personally I like RetroArch over individual emulators for simplicity. Can recommend SameBoy & Gambatte for GB+GBC, mGBA for GBA, melonDS DS for NDS, & Snes9x for SNES. All are accurate (so not likely to make a game bug out) & run fine on my midrange phone.

The touch controls work fine for games where timing/precision matters less, and for the rest I just use a BT controller. Xbox & PS ones are compatible, I believe, & there are some great quality 3rd party ones (like 8bitDo) out there.