Authentication and authorization can both be done with a signature.
For the signing party: the ability to provide a correct signature means that he has the private key.
For the verifying party: passing the signature check guarantees that the message content has not been tampered with and that the source of the message is reliable.
I can also establish that the address belongs to me in Bitcoin by providing the following information:
Select the signature symbol → click Connect Device → select Message, enter the content you want to sign in the text box and click Confirm
Click Verify → Verification Passed
Anyone can verify using a wallet tool or a third-party service.