I use Vanilla Music. It does folder play particularly in a way I want, where it adds the songs randomly into a queue, which shows me how many songs are left, lets me manually move them around, etc.

It also seems to have a lyrics search plugin, but I don’t know if that means lyrics support in the way you want.

I’ve been using VLC for folder based play of audio files. The UI is not ideal but it works well and the other apps I’ve tried didn’t work out for various reasons. Unfortunately the Android Auto version of the UI doesn’t have access to the folder browsing feature.

No idea if VLC has lyrics support for audio-only files.

Phonograph Plus

Thank you, guys !

InnerTune