I just can't believe Duo doesn't have a desktop app of some sort, even if super basic. We use this where I'm at and I have to grab my phone while sitting at my desk to 2fa into things so many times a day. I use Authy for a lot of other stuff and it has a little chrome webapp/extension that'll let me not constantly grab my phone.
Random thought, they have apps that mirror your iPhone screen, typically for development or presentations. You potentially could use that as a workaround so your phone just needs to be connected or on the same network etc.