Well although ID .me might not be long for this world, I had a go at registering this morning. Here's my experience:
Firstly I'd tried previously but failed due to the non-US address and non-US phone number. ID.Me had sent me an email asking if I wanted to continue or go directly to the video referee - I hadn't really paid attention to that previously, but selected that option. This took me to a different registration page and allowed me to enter my UK address, didn't ask for any telephone number. Then uploaded copies of my passport, social security card and a UK utility bill (Vodafone broadband).
This then took me to the waiting room - my wait time was 7 Minutes - YES - SEVEN MINUTES!!!!
I was actually in to the call in less than 4 minutes, video verification took about 3 or 4 minutes and that was it. Email received, and I'm into my IRS account.
I started and submitted my documents @ 9:58am this morning.
At least I now know the IRS has not yet processed my 2020 paper filed return (my own fault as I field late - mid December).