Just a minor procedural sidenote—starting a new pre-PEP on your fork, usually with a new dedicated thread in this Discourse category to discuss and refine it until it is ready for submission as a formal draft PEP, is the way to go. However, do note we cannot necessarily allocate it a particular PEP number until it is at the stage of a formal draft PEP, is submitted as a PR and passes a preliminary round of editorial review, so by convention PEPs before that stage are named pep-9999.rst and renamed once the PR is ready to merge.
EDIT: And just to be clear, it we’re definitely not at the formal draft PEP submission stage yet.