I have heard good things about the keychain way. I think it is more intended for in-person onboarding.
In my case, at a virtual conference, I think the QR code will not work.
Maybe it would work? If the conference attendee can screenshot the QR code and send it to me somehow.
Yes, works better in person, and you can have it done in less then a minute.
But a screenshot would probably work to do remotely.