I would bet that Apple would still require developers to sign their apps, like they do on macOS. That means you that if a vendor does something particularly eg

I would bet that Apple would still require developers to sign their apps, like they do on macOS. That means you that if a vendor does something particularly egregious, stuff akin to malware, they can pull the certificate for that vendor. They don’t do that often: IIRC, they’ve only done that in macOS a handful of times.