It's now easy to add support for all unsigned.io boards in the Arduino IDE! Just go to preferences in Arduino, and under "Additional Boards Manager URLs", add the following URL:
If you already have other URLs, separate them with commas. You can now go into "Board Manager", scroll down and install "UnsignedBoards". That's it! The Arduino IDE now has native support for all unsigned.io boards.
Adding the boards to the Arduino IDE in this way also includes any libraries that you might need to use, like LibAPRS and LibRNode. The library will be updated when new boards are released.
The board support files are based partly on MightyCore by MCUDude.