My mobile radio projects are mostly centered around the 900MHz band. The very first was to tune up an old cell phone to the band, these days there is enough commercial equipment available that can be reused.
I have experimented with two different 900 MHz radios, the TK941 and TK981 from Kenwood. I use the TK941 for repeater building, and the TK981 for mobile use.
The 981 has an interesting built-in data mode that I have been able to use as a general purpose KISS TNC. Kenwood calls this mode ‘Fleetsync’, which I was able to adapt to transmit APRS-IS messages from a cellphone back the the repeater.