I followed those install steps after the ones I normally try, at https://wiki.postgresql.org/wiki/Apt, led to a message that pgAdmin was not available for Hirsute.
In any event, the application icon now appears in the Activities overview, and I can launch pgAdmin successfully.
Question:
In past pgAdmin installs when I used the steps on the PostgreSQL wiki, I was able to launch pgAdmin by entering "pgadmin" at my Terminal prompt. This does not work under my new install. Is that expected behavior now that pgAdmin is a standalone app?