You can use pixelfed with the same account, but to do this you will have to go onto your mastodon instance and follow a pixelfed accounts from there and they will appear in your Mastodon timeline. Here is a little explanation of the “log in with Mastodon” option.
100%. This is exactly why I switched my home server over to NixOS and would struggle to go back. I used to reinstall all the time but now there really isn’t any need to, since I can just look at my configuration.nix file and know everything that’s installed, running and configured on my system. Whereas using any other distro I’m like WHAT ON EARTH IS RUNNING ON HERE?