Actually, Option 1 does not do that, as test-extra, test.extra and test_extra (and test--extra and test.extra) are all left alone, not normalized to one common form. The only change that Option 1 makes to PEP 508-valid extras names is normalizing test__extra to test_extra. This is the fundamental difference between Option 1 and Option 2 (and why you’re not seeing different spellings of dev_lint get normalized to the same name).
I did previously do some limited testing of this which appeared to suggest at least some current tools reject extras that have non-PEP 508-conforming names, at least in some contexts. However, I would be concerned that tools should be tolerant of extras produced by older or other tools that may not have conforming names, given the current situation.
Given my background and expertise being a pretty good match for that and it being a more valuable use of my skills than copyediting others’ PEPs, its something I’m been meaning to offer to help with as one of my next projects, but I want to finish PEP 639 and some remaining PEP infra/documentation work before overextending myself further.
To be fair, we have a PEP (clarifying this being part of the motivating purpose for said PEP), so isn’t this a moot point as we can just specify it there (as PEPs are change proposals to the existing canoncial PyPA specifications, rather than standalone specifications)?