Oh! I missed this one because I've been looking specifically at the Packaging forum rather than the PEPs forum. This looks like a brilliant use case. (I'm aiming for wide compatibility - back to 3.6 - with my current projects, but I look forward to trying this out if and when it's accepted and implemented.)

Now if only the overall `subprocess` interface weren't so complex....

We really should just point most of these comments at that PEP. Thanks for getting it out so fast.

PEP 787 – Safer subprocess usage using t-strings https://peps.python.org/pep-0787/

Hmm, PEP-787 has some interesting discussions around it. I'll have to sort my thoughts on these aspects a bit.