Most people don't put much stock in "EV" certificates though, which to me would be the equivalent of the signed app, sort of, as it demonstrates that the person you are talking to is a specific known legal entity, sort of like demonstrating the app you are installing came from a specific known legal entity.

The "ordinary" certificates we use just are meant to prove the website you are talking to is the authorized owner of the domain you mean to be talking to... I'm not sure if there's really an analogy with installing apps, that kind of cert is I think maybe meant to protect against a kind of attack only relevant to network communications, not app installs.