At to switching to pgAdmin4, I have that up and running, but there is no equivalent to the server status functionality in pgAdmin3 as far as I can tell. I did a search on the Internet to see if pgAdmin4 offered similar functionality and the posts I read indicated it did not.
I realize pgAdmin3 is out of support, but I've seen at least a half dozen projects that have forked it and are attempting to get it to work with later versions of PostgreSQL 11 and 12. I'm investigating building it from source now with some of the various patches from these forks. Would be very interested in either getting involved with one of the projects that has forked pgAdmin3 or possibly pulling out some of the useful functionality like the server status capability and creating a separate application (maybe with a different user interface library). I build and personally maintain several C/C++ projects that are no longer officially maintained by other developers. Would have no issues with maintaining and using a project that had no official support as long as I could compile and debug it myself.