I use a FOSS voice recorder app from F-Droid. It's just called "Voice Recorder" with an orange icon. It does exactly what it says, records audio from your microphone, lets you play them back. They're just files on the device.

Anytime I need a "simple" utility, I check f-droid first to get the one-trick-pony app over spyware from the play store.

Other utilities I use are: WorkTimer: pomodoro app DiskUsage: self explanatory Http Request Shortcuts: setup home screen app shortcuts that run http requests