Short answer, it's a more or less a self contained environment for running applications. Docker is more developer friendly, a similar technology kubernetes is more dev ops focused.
My advice to anyone using pgadmin4 is to try running it in Docker.
I replied privately to George with more details. I can forward all that here if people want.
You might end up using Docker only for pgadmin4 but once you get used to using it I think it will be a valuable tool for you. The longer I use it the more places it fits in.
[Ken Benson]
I’m curious – what is Docker and where can I find some information on running PgAdmin 4 in Docker?