requestDevice supports filtering by service UUIDs, but seems to still not support filtering by Manufacturer data?

Correct. Filtering by Manufacturer Data is not supported yet.

Is filtering by Manufacturer Data something that may exist soon, or should I go with an alternative method?

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

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