Today we use read only connections for production databases and it works well. But everyone once in a while we do need to change a value in a production db.
Today we then connect with different credentials which takes a little time.

My suggestion is a connection that linqpad enforces with fingerprint, windows hello or similar.
So the connection is always there (and read/write) but every time I want to use it I have to authenticate. This would still be much faster then creating new connection (and in the other scenario I also have to remember to disconnect manually but here you could time out)