As I mentioned elsewhere, there is a case for providing json-ld metadata - which is already in use and has been blessed by Google (not that I care) and dumping both OpenGraph and X/Cards in favour of open standards over proprietary and non-extensible solutions. The Alphabet currently only blesses @context values using schema.org, but this is where the fediverse can assert a standard context that works for us and just start using it. And it's already defined!.