I think what probably happened is when I was initially stuck, and trying to run pgadmin4 from the terminal, not seeing anything happen, and thinking it was not fully installed when it was, I started monkeying around with the urls in /etc/apt/sources.list.d to try uninstalling and reinstalling past releases, following a bit too blindly things I found searching online...
garrett@garrett-external:/etc/apt/sources.list.d$ ls
deadsnakes-ubuntu-ppa-impish.list pgadmin4.list.save pgdg.list.save
pgadmin4.list pgdg.list
Looking at pgadmin4.list.save , I see I had at least tried to use hirsute 's repo:
garrett@garrett-external:/etc/apt/sources.list.d$ ls
deadsnakes-ubuntu-ppa-impish.list pgadmin4.list pgadmin4.list.save pgdg.list pgdg.list.save
garrett@garrett-external:/etc/apt/sources.list.d$ sudo rm pgadmin4.list.save
double check that the pgadmin4 sources are correct...
garrett@garrett-external:/etc/apt/sources.list.d$ ls
deadsnakes-ubuntu-ppa-impish.list pgadmin4.list pgdg.list pgdg.list.save
^ok definitely the problem...should fix that....
uninstall pgadmin4
garrett@garrett-external:/etc/apt/sources.list.d$ sudo apt purge pgadmin4
garrett@garrett-external:/etc/apt/sources.list.d$ sudo apt autoremove
reinstall pgadmin4
garrett@garrett-external:/etc/apt/sources.list.d$ sudo apt update && sudo apt install pgadmin4
And now it works fine