You'd have to be more specific about "GPIO pin" and 'other interfaces'. CM108/119 devices work exactly the same as would things like RTCMs. Other "GPIO" things would work as per Debian 12 or 13 have traditionally worked for those operating systems - we don't make anything non-standard in that regard.
At the minute the RPi interfaces into a pair of Motorola GM340 radios and sensors, to capture data such as temperatures from various devices.
Does ASL3 have a baseline standard for how these hardware interfaces are set up at the point of the GPIO pins which are assigned for different purposes.
Apologies if this is basic stuff, but I have no documentation for the versions of HamVoIP currently installed, nor any configuration management docs for the installation.
So starting from scratch with a clean ASL3 should solve a lot of issues and I can create the config management docs as I go.
Assuming your "RPi interfaces" to the GM340s means normal CM1xx-compatiable audio adapters than nothing will change with them except possibly a one-time change in the devstr= for the simpleusb.conf/usbradio.conf configuration.
For "sensors" that could vary widely depending on the hardware. If you're talking about I2C sensors, the pins in the PI board would be exactly the same SDA/SCL pins as well as any needed power. How that old version Arch Linux (which is what HamVOIP was based on) named that may be different from the standard conventions on a Raspberry Pi. However ASL3 is based on the standard Raspberry Pi OS 13 / Debian 13 Trixie so all online directions for anything about I2Cs on Pis would be accurate for an ASL3 device.