There's no way for your ISP to know what software you're running.

Gatekeeper checks if your app is malware (or not) and if its been signed with a valid Apple developer certificate. The OCSP look up goes over in the clear currently, but that's how OCSP works everywhere. Your DNS provider can see the OCSP lookup but that's about it.

Apple is in the process of addressing this; you can read the details of how the current process works at https://eclecticlight.co/2020/11/16/checks-on-executable-cod...