Package Managers need global hooks

So your solution is to reinvent signature based antiviruses, like Norton Antivirus and McAffee?

The problem with these 2000s approaches were that attackers could:

1- Fuzz their payloads so that they are never the same and they don't trigger detection.

2- Offload payload mechanisms so that your monitoring system needs to play cat and mouse. For example, what if the malicious code does wget https://IP/file, will you detect wget commands? Will you scan for whatever looks like a URL? Ok, what if they do "another_package_manager_like_flatpack malicious_package", will your scanner implement all package managers? What if they construct the url? "protocol + "://" + domain + file" surely your global hook thing will notice that is a url and how it is downloaded and inspect those contents as well?

3- The attacker can control the timing and infect every user at the same time, especially if they control the update mechanism of users whose security policy is to keep things patched. Even if the malicious update is not simultaneous, the malicious update can start distribution, and the attack only triggered months later (simultaneously) when enough users have downloaded it (beating latency policies).

The only solution is to do actual work and either write the thing you are trying to offload to the 'open source community, or to actually write it yourself. But of course more work is going to be put into the possibility of a magical easy solution, than on an deteriministic hard solution.