How to connect to remote PostgreSQL URI in pgadmin

I’m running NixOS and trying to follow this simple example of usage of PostgreSQL on shuttle.rs.

I have managed to deploy the app on shuttle.rs and have received a postgres://... URI for the server hosted there. At this point the above instructions blithely state

connect to the database provisioned by Shuttle using pgAdmin using the provided database URI […]

Looking on search.nixos.org I find pgadmin4 which I try to run with nix run nixpkgs#pgadmin4 and it errors with

ERROR  : Failed to create the directory /var/lib/pgadmin:
           [Errno 13] Permission denied: '/var/lib/pgadmin'
HINT :   Create the directory /var/lib/pgadmin, ensure it is writeable by
         '<my-local-NixOS-username>', and try again, or, create a config_local.py file
         and override the SQLITE_PATH setting per
         https://www.pgadmin.org/docs/pgadmin4/8.6/config_py.html

In short, pgadmin4 seems to require manual local changes to the state of my NixOS machine, when all I want to do is to connect to a remote instance of the DB. I do not want to run PostgreSQL locally.

Please help me clear up my confusion.

Try nixpkgs#pgadmin4-desktopmode