!d sounds good and makes teaching easier. Adding additional symbol sort of clutters the experience in f'{name!!}'. I think it will be a good thing to have it in 3.8 since it serves one of the common things in debugging f'name = {name}' and perhaps it could be expanded out of f-strings after feedback.

Rust also introduced similar feature with https://doc.rust-lang.org/beta/std/macro.dbg.html and received very positive feedback . This will be a very exciting thing to look forward in 3.8 :)