If I do
ip ssh source-interface g0, that restricts:
- which interface the Cisco device listens for SSH connections,
- which interface it is allowed to use for the client to connect to other SSH servers,
- which interface all SSH packets go out and/or permitted in (implying both 1 and 2), or
- None of the above.
Experimentally, it looks like 2, which is not what I had intuited originally, thus prompting the question for confirmation.
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/security/d1/sec-d1-cr-book/sec-cr-i3.html#wp5893687220 -- Ref that seems to agree with my experimental conclusion, but I've been wrong trying to follow Cisco logic before.