With the release of the Raspberry Pi 4 comes a new release of Raspbian, "Buster". We have successfully updated our code to run on Buster and can now support the Raspberry Pi 4.
I have successfully tested the PTT from Direwolf using the GPIO pins on the raspberry pi. This removes the need for a VOX circuit and the associated problems.
We have successfully sent a APRS message packet over RF and was received and decoded by Gqrx.