Using Physical Security Keys

I've previously read all of the Apple material on this subject, including the article for which you provided a link. That article seems to suggest that I wouldn't be able to sign in on my MacBook without a hardware key, which would leave me in a bind since my MacBook OS can't handle keys, as noted in my original post. However, I believe my MacBook and iPhone are considered "trusted devices." For example, if I log into my Apple Id account web page from the iPhone or MacBook, a hardware key is not required. But if I try that using a different device, a key is demanded. So the real question boils down to whether my MacBook would be recognized as a trusted device and be allowed to log into the Apple Id account web page should the MacBook ever get disassociated from the account in some way.

Today I ran an update to macOS. The setup procedure at the end of the update required me to log in to my Apple Id account. The login wanted my Apple Id and Password but did not ask for hardware security keys. So, I suppose that answers my own question: that Apple is recognizing my MacBook as "trusted" and thus not requiring the hardware keys. I still feel uneasy about this whole question though. If anyone knows more, I'd like to hear from them.

But apparently this is precisely what happened, as noted in my most recent post. The fact that the macOS update procedure asked me to log in surely means that the update process logged me out at some point. Hence I was logged out, and then I logged back in as requested by the last steps of the update process. Hardware keys were not requested.