According to this ArchWiki page on package maintainers You don't have the requirements to maintain packages on the extra repository as, you have to have a few AUR packages beforehand. Your PKGBUILD looks fine however. You can keep your PKGBUILD on the AUR; there are many examples of upstream developers maintaining an AUR package such as Librewolf and SwayFX.
Good luck with your project! Keon Cachia
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