Yeah, I think I agree with you.
And I think having syntactic convenience for partial does not make much sense if partial lives in functools - it is fairly high level import.
So the only way for that would be to implement it at lower level.
And that would be a very long shot…
Yup. Compared to your initial implementation this indeed feels so.
Backticks have faced a significant resistant historically (can’t remember reasons, some might be in Backquotes for deferred expression) - minuscule chance for pulling these through for this fairly niche application.
\ makes it look like latex. Also, long shot. See Python Idea - Latex style macros
! is probably nicest and most reasonable. But also, unlikely that the last reasonable one-character operator would be accepted for this specific application.
Ah and also, in the long run, I am placing my bets on PEP 638 – Syntactic Macros | peps.python.org, which intends to make use of it.