You can fix the loading of js8call and wsjtx by using sudo apt-get install ./$findname instead to sudo dpkg -I $filename. Apt will resolve the missing dependencies. It just needs to know it is working with a local file - thus the ./ prefix.
I have followed this but can't get the drivers enabled. When I have dtoverlay=vc4-fkms-v3d or dtoverlay=draws,alsaname=udrc enabled in /boot/config.txt my Task Bar on the screen goes away and aplay -l says aplay: device_list:272: no soundcards found...
Maybe the drivers aren't compatible with the new SOC.
73 - Frank - K0FEI