@puppygirlhornypost2 Short answer: Almost certainly not, with caveats.

Long answer:

1) Actual glow-in-the-dark (charge it up and it glows without further illumination) pigment: zinc sulfide with copper activator is approved for use in cosmetics but under very restrictive rules: facial makeup and nail polish only, and for infrequent use rather than daily wear. It also must be labeled with a warning to not use near the eyes.

Based on that, I would strongly recommend against using it on anything that's going to contact mucous membranes.

2) The two main fluorescent/black light glow pigments (requires blue to UV-A illumination to glow) in common use are fluorescein and pyranine.

Fluorescein is used medically, most notably for inspecting the surface of the eye for scratches etc. A small number of people have experienced anaphylactic allergies to it, but if you're not allergic it's otherwise relatively nontoxic for skin contact. It won't glow in dry powder form but glows bright green in a water solution.

It's sometimes used in shampoos and soaps as a dye, and I also found an Australian study [1] that mentions its use orally as a tracer dye with a small number of patients reporting minor stomach upset but otherwise an excellent safety profile. There don't appear to be any human studies of its use on genitalia specifically but of the options, this is the least likely to be problematic given that people intentionally put it in eyes, swallow it, and inject it for various medical reasons.

Pyranine is used commonly in yellow highlighters, and does appear to be used in some cosmetic applications (aka D&C Green 8) but there seems to be a lot less data on its safety profile vs fluorescein so it's probably a riskier bet.

Tl;dr if blacklight green glow is OK, something homebrew based on fluorescein miiight be OK as long as nobody is allergic, but you're still taking a risk given the lack of data on its use for this application. Actual zero-light glow is likely a horrible idea.

[1] https://www.industrialchemicals.gov.au/sites/default/files/Fluorescein%20and%20its%20sodium%20salt_Human%20health%20tier%20II%20assessment.pdf