Nextcloud Password, or you can store your KeePass vault on your Nextcloud if you want.
A few years ago I wiped all my devices when I was in a state of bipolar mania. I was eventually able to regain access to my Google account, but I had to go through so many steps and it took about a week. Important points: 1. I was able to regain access after nuking all my devices 2. But it was REALLY hard! Knowing my password was not enough.