Provide subjectAltName to openssl directly on the command line

Subject Alternative Name

What is an Object Identifier (OID) in PKI? How do you obtain an OID?

OID Repository

Is there reserved OID space for internal enterprise CAs?

Inserting Custom OIDs into OpenSSL — contains error or outdated information; in the last example one should specify syntax like this: MyOutstandingOID=ASN1:UTF8String:Hubert Dean in the last line of the config for it to work with modern OpenSSL

How to specify the Syntax for Values of Private OIDs while configuring in OpenSSL? — contains an explanation of the problem in previous point

Alternatives to HTML's deprecated <keygen> for client certs? — generating certificates in a browser

How to Be Your Own Certificate Authority — contains outdated and/or suboptimal suggestions, but great for showing the general strategy