Mobilink tncs are really nice but you're still limited by APRS.
When I discovered Meshtastic, I already had some of the Heltec modules around, which are reputed to have the worst RF performance. I tried anyway, and indeed, I had to equip some truly silly antennas to get even a mile of range. (18dBi yagi in my living room, pointed at a parking structure downtown, was able to talk to another node on top of the structure with a 6dBi omni. Just barely.)
I've been pursuing other projects since then, but a quick skim of the meshtastic forum suggests that there are some much better-performing RF modules now. I'll play with those soon enough...
And anyway, there are encodings other than the patent-encumbered LoRa worth considering, too. (The LoRa folks just did a stellar job capturing mindshare lately.) Really, a feature-set identical to the original IM-ME, but with an option to use ham radios to extend the range, is what I want.
By now we have very efficient modulation like FT8 and LDPC error-correcting codes, so I think it should be possible to do much better, even within Part 15 limitations.
I'd love it to have three radio decks: One ham transceiver, so I can use direct APRS-or-whatever with other nearby nodes or digipeaters, though I know the antenna will suck. One Bluetooth, so it can act as the QWERTY UI for a more powerful radio that lacks a decent keyboard (or as a generic peripheral for other projects). And one Part-15, perhaps LoRa or something, so it can also operate in an unlicensed mode with Meshtastic or something as the protocol over longer range than Bluetooth.
I'm pretty sure I could design the hardware, both the electronics and the enclosure, but I can't code my way out of a wet paper bag, so that's sort of a non-starter.
The bigger question question is, why doesn't this exist yet? Are there HTs with native Bluetooth so the texting UI could be implemented as a phone app? I know there are some with Bluetooth for other functions but I'm not clear on whether they can act as a KISS TNC over SPP.
If so, that would be a great interface to standardize on, implement the phone app for testing, then turn it into a physical gizmo to enjoy longer battery life and cheaper/rugged hardware. Then as a next step, bring the Part-97 hardware into the gizmo.