Check out the community lemmyapps (not sure how to link yet), it has them all listed. I personally like Connect.

https://lemmy.world/c/lemmyapps

Two. One for lemmy.world but then due to the issues, moved to lemm.ee which is my current main.

If you click that link on your phone, it should open your 2FA app and add it. Alternatively, you can get browser extensions to convert it to a QR code and scan it like normal on your phone.

How does this work for a google account that I’ve got linked in gmail to my standard google account? Is that classed as active or do I need to login to each one manually still?