I'm aware, which is why I specified "primary/signup device" in my original comment.

Is the desktop client a "first class" one? Can I use it exclusively, including for initial signup?

A sibling comment implies the answer is "no", but it's ambiguous, since "linking" could just mean the SMS validation, which, IIUC, need not actually match the phone number on the device [1].

[1] presumably a tablet would work and does not necessarily even have an associated phone number, but that's still not a desktop.

But it still requires you to link it to a phone before using.