I guarantee that if you’re here, you’re very likely to be extremely tech knowledgeable (compared to the large populace)

a phone needs to be able to make calls and send or receive sms…

Eh, there’s always something people with a lot of tech knowledge think are obvious to people without a lot of tech knowledge. Just look at the mess that Linux can be.

If I understand correctly, this thing turns your phone into a computer. But I need a phone…

To add to that, Maperitive is a fantastic piece of software (Windows only) to create your own custom maps for hiking or cycling with osm. A bit tough to wrap your head around unfortunately, but actually pretty powerful. Hmu if you need quick instructions