MII is not RSA, it's an opening header of asn1 structure encoded to DER -- 30 82 0x which is basically "{" when which can be pretty much anything from x509 certificate to private keys fro ECDSA.

Actual RSA oid is somewhere in the middle.

True, but for the most part, RSA keys are the only keys that anyone encounters that start with long SEQUENCEs requiring two-byte lengths.

`eY` could be any JSON, but it's most likely going to be a JWT.

Neither is a perfect signal, but contextually is more likely correct than not.

That depends on the kind of abyss you are staring into. Mine had plenty of non-RSA keys, certificates (which are of course two-byte length all the time) and CMS containers.