That's not quite how it works with the FDA. One thing you have to be able to do is demonstrate reproducibility - so an exec + toolchain is easier, but there is

That's not quite how it works with the FDA. One thing you have to be able to do is demonstrate reproducibility - so an exec + toolchain is easier, but there is no reason that you couldn't in principal do the same thing with source + toolchain + test. There is more to it, of course. More importantly though, there isn't such a thing as "certification". You can go through a PMA or 510(k) to get "approval to market" for a restricted set of claims based on your filing, leading to "indications for use". This wouldn't really apply to an open source project unless someone were selling it an making claims on how it could be applied. In the US, clinicians would have fairly broad power to use a product "off label" if they chose, and the FDA doesn't control anything around what you might choose to use on yourself.