I hope this is not totally over the top, but I guess FIDO2-based authentication might get more important. I refer to FF (for example) requesting for the FIDO2 device being plugged, the PIN being entered, the device being touched, etc. See https://webauthn.io/ as a test page.

I currently don't have a concrete use case for this on HtmlUnit, but might get one in foreseeable future ...

BTW, thanks for maintaining and developing HtmlUnit!