Some updates from the Bluetooth side of things for the Newton: I have been able to compile Blunt 2 on Linux using mosrun, the excellent Mac OS enabled 68k emulator by Matthias Melcher. The only pieces missing are packing the compiled binary, and embedding it into a Newton package. This should finally allow to cover any scenario of Newton development without the need of Mac OS Classic.
I have also looked again into suitable Bluetooth modules, and it seems that the HC-05 module, some quite interesting options exist. The module can be purchased for 5-10$, it has an integrated antenna, and uses 3.3V as the power supply - it should be pretty easy to connect to the Newton’s internal serial connector. By default, it is configured to act as a Bluetooth slave exposing a serial port profile, which is already quite useful: In this configuration, the Dock protocol can be run over Bluetooth without changes (only the internal serial port needs to be made visible to the Dock app). It won’t allow establishing a connection from the Newton to any other device to use e.g. Neo and IC/VC, but for backup, syncing and package installation this would be good enough.
The HC-05 module should be reconfigurable though to use HCI as the Newton-side protocol, and this would make it a great candidate for Blunt. The only challenge is to implement a LPT to SPI converter and use the CSR tools to flip the configuration bit for HCI support.