To the great apps verybody is mentioning I want to add

Gadgetbridge

this app allows sync to a large number of smartwatches, so you don’t have to use the privacy nightmare proprietary apps from the smartwatch vendor. In my case I use it with an Amazfit Bip, and it works well

Osmand Plus (free, Costs money on PlayStore) - Who needs Google maps anyway?

Termux is essential as well.

But I really can’t live without NewPipe.