microg passkeys will arrive with /e/OS v3.3 probably sooner than end of Dec - and works if you meet the criteria.
At least one biometric must be enrolled to create keys requiring user authentication for every use
there’s no key backup / sync mechanism yet, treat it as experimental and have working account recovery methods if you use it.
(also: as this patch isn’t in the e cromite fork yet you’ll need another browser to call the credential manager)