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I doubt that would be possIble as they are not super closely related, jambu does fruit fast though
Quince and pear are both unusual in that regard, graft compatibility beyond the same genus is pretty rare in plants. Pear is also compatible with rowan and in some rare cases can be compatible with some apples. Myrtaceae in particular seems to often have incompatibility even within the same genus. Some Psidium species aren't even compatible with other Psidium species, same for many Eugenia species being incompatible within their genus. I've never heard of any Myrtaceae species being compatible with any species in a different genus.
Wide compatibility tends to be much more common among species that graft readily. Myrtaceae does mot graft readily. One of the reasons suggested for low compatibility in myrtaceae is a high level of phenolic compounds that inhibit calus formation.