I know very little about AGB_FIRM. But in any case, AGB_FIRM would need to implement RTCom or something similar to communicate with the Arm11 to read the gyro data. And I'm not even sure if this is possible, according to gbaTek/3dbrew the legacy RTC registers (utilized by RTCom) can only be used for this purpose in DS mode.
Actually, gbaTek and 3dbrew
mention registers that are used to emulate the RTC there. But even if it works, it would require patching both the AGB_FIRM (to pass the gyro data through the RTC) and the game (to accept that data from the RTC and use it properly). Too much hassle for one game.
These patches do work directly with TWL_FIRM. nds-bootstrap only gives you the ability to run AR cheatcodes, and even that is unnecessary since roms can be patched directly beforehand (like DeadSkullzJr's xdelta version of the SM64DS patch ).
Theoretically, this should be possible. It would require implementing a way to read the Circle Pad Pro through the IR port. But I don't have this device, so I cannot do that. Also, it's probably pretty hard to do. The CStick is simple because it's just an I2C device. Even though TWL_FIRM knows nothing about it specifically, there is already everything we need to communicate with it.