ID1 v ID3 v ID5 proof of identity

I've been quoted ridiculous prices by local solicitors to complete their part of ID1 so I'm thinking of either

1) doing it online via video which involves getting ID5 completed, I've seen a firm advertising this for a reasonable sum but I wondered if it was still acceptable to you as I gather it was introduced during Covid times? For example the website id5.co.uk says you accept it for compliance but you always wonder on the internet. I assume if it's acceptable I complete ID1 myself and they complete ID5 and I send them to you when I've received the ID5 from them?

or

2) using ID3 and I noticed the notes re who can complete it imply that anyone retired from the professions listed can complete it but the list itself in 2.1 only refers to retired legal professionals. Can you clarify please as I know several retired teachers and would save money!