Related to my previous post which is now closed and I cannot add a comment. I wanted to share a finding in case any other Firefox user comes across issues using passkeys that I encountered.
The issue described on that linked post was that whenever I tried to add a passkey with Bitwarden, using Github as an example, the bitwarden pop-out box would fail by attempting to open in a new tab. It was suggested I try reinstalling the add on which worked for me in the first instance but the issue started up again, after I had marked as resolved.
I iterated over my add-ons switching each off and trying again and was able to isolate the cause of my issue, ‘Sticky Containers’ which I use in conjunction with the popular Sideberry add-on.
Temporarily disabling the Sticky Containers extension allowed me to save and use a passkey. It makes sense, the extension keeps newly openned tabs in the same container as openned in, which I guess interferres with pop-ups. I had event tried to completely disable pop-up blocking yet the issue remained.
In case anyone using Firefox is having a hard time creating or using passkeys, or issues where the bitwarden pop-out window fails, temporarily disabling Sticky Containers worked for me.