You also forgot 60, 30 and 10 (at least in the US) 

 While RadioMail is primarily focused on portability and despite being designed for iPhone only, almost a quarter of RadioMail usage is on iPads. It does make sense to want to use a larger screen and a keyboard for email management, when available. And by extension, having the ability to run the app on an Apple Silicon Mac seems like a logical step as well.

When more than one device is used by a single account, it becomes critical to be able to synchronize messages across those devices, which has been a frequent request. That will be our next area of focus.

Current thinking is to develop a new version of RadioMail, optimized for devices with larger screens and keyboards like an iPad. This version would include all the current features, plus:

* An interface optimized for iPad screens, featuring a three-column layout similar to Apple Mail.
* Synchronization of messages and settings between the iPhone and iPad versions.
* Compatibility with Apple Silicon Macs, running as an iPad app.

As for a TNC, a version with a built-in 1200 AFSK packet modem is being tested right now. It leverages the DigiRig Lite sound card and DigiRig VOX cable that can be used from iOS. Once that's released, a direct WiFi connection to the IC705 & friends could be considered. However, the lack of documentation for the RS-BA1 protocol make it difficult to predict how robust of a solution can be delivered. https://github.com/nonoo/kappanhang has done a great job making it work, but the amount of "magic numbers" used in the code is somewhat unsettling. 

 Consider starting as simple as just making the iOS version available on the M Macs. The UI is good enough. Then make the better version. 

Regarding the TNC, anything should be easier to use than direwolf, even if not perfect. Maybe reach out to SDR-Control app dev (I think he's name is Marcus), he might be able to help. He did reverse engineer Icom/yaesu/Ken woods interface to perfection :)