That should be asked of that of their support since that isn't if so a Mozilla product.

A BIG thank you but sorry, too dopey to understand that, simple though it will seem to the initiated.

I think that it should work (CTAP2 is enabled; security.webauthn.ctap2). Did you try it recently?

No, thanks for your answer - I've only just found out about yubico so was exploring whether it was compatible with FF/Mozilla. I've read conflicting answers, but not being an expert I just need a yes and how to, or no.

Since that isn't a Firefox browser or Mozilla product and if you don't want to ask that software company what works with their product then there's nothing more that can be done as your asking the wrong forum rather then communicate with yubico support to get the right answer about compatibility.