I do not want any business with Apple/Google/Microsoft at all, including owning an Android or iPhone for hardware attestation.

You don't need to use anything from Apple/Google/Microsoft. Passkeys are just WebAuthn which is an open standard.

	▲	debazel 4 hours ago \| parent [-]
		An open standard that has attestation in it which allows sites to block all open implementations. FIDO Alliance spec writers have even threatened that apps like KeepPassXC could be blocked in the future because they allow you to export your keys.