I'm happy to participate, but we don't have a process yet.
Let's say I do audit a specific version of a dependency I use. How do I communicate to others that I've done this? Why would anyone trust me anyway? I've mentioned that 'm not an infosec expert; how much is my audit worth?
I have before run programs inside firejail and watched for network activity where there shouldn't be any, but even if that is a useful activity, how do I publish my results so that not everyone has to also run the same program in firejail? What do non-technical users do? And this active approach has three problems: 1) you'll only see the malicious activity if you hit the branch path of the attack; looking for it this way is like doing unit tests by running the code and hoping you get 100% code coverage. 2) These supply chain attacks can be sophisticated, and I wouldn't be surprised if you can tell that you're running in firejail and just not execute the code. 3) This approach isn't useful for programs which depend on network connections, or access to secrets - some programs need both. In an extreme example, there'd be no way to expose a supply chain attack embedded in a browser, which often both has access to secrets and who's main purpose is networking.
The main problem is that we're in the decade of Linux, and a whole population of people are coming in who are not nerds. They're not going to be running strace or firejail. How are we going to make OSS secure for these people?