The application/manifest+json media type should be registered with IANA "[o]ne to two months prior to Candidate Recommendation" (https://www.w3.org/2020/01/registering-mediatypes).
Emailed IANA. Blocked on waiting to hear back. I don't expect any issues with the registration.
Next step will be to fill the IANA form.
Reminder to fill out the actual IANA form.
Form filled out and sent. Progress can be tracked at:
https://tools.iana.org/public-view/viewticket/1198833
I validated the request on the W3C side.
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I validated the request on the W3C side.