Isn't it simpler just to have 1 service managing your credentials? Bitwarden is free and open source and you can just disable Firefox's native ability to manage them so that you aren't seeing both trying to save an item.
Regarding the comment above about losing your biometrics, I would be fine with biometrics as a complimentary option so that both are available but offers quicker access.With passkeys available now, has any thought been giving to this? It also reduces...
