Does firefox ios let you use a password manager? I have both bitwarden and proton pass installed and I'm unable to use either of them. I didn't have this issue on chrome or safari
I'm using Firefox on my iPhone. It fully integrates with the regular iOS password manager prompts, messages, and system. This means things like 1Password and Bitwarden will too, as they hook into those same interfaces.
Head to "Settings", then "Passwords", and under "Password Options" you will be able to select the app or storage service of your liking: