kv4p HT is a homebrew VHF radio that makes your phone capable of voice and text communication completely off-grid [...] radio simply plugs into the USB C port on your Android smartphone and transforms it into a fully-fledged handheld radio transceiver.

Looks really cool. But then of course I know nothing about ham radio.

I have multiple Raspberry Pi's, but there are so many similar products out there!

The Raspberry Pi has spawned a world of single-board computers in the same form factor, often with the same standoffs. For example, the Pine Rock64 for an alternative ARM option, the UP 7000 for Intel, and the Milk-V Mars for RISC-V. I’m extremely keen to try all these out.
https://rubenerd.com/building-a-homelab-cluster

• https://pine64.org/devices/rock64 a well-established SBC
• https://milkv.io/mars (I wonder which OSes would work with RISC-V architecture?)
• Pine StarPro64 RISC-V SBC with up-to 32GB RAM announced