I was on the Eclipse Foundation call a few days ago regarding this topic and they said there was a well-established 3-part test for this in the EU courts. But I don't think I managed to take a screenshot, sorry.

Here is a snippet from the EU Blue Guide linked the from the Eclipse blog post:

"Commercial activity is understood as providing goods in a business related context. Non-profit organisations may be considered as carrying out commercial activities if they operate in such a context. This can only be appreciated on a case by case basis taking into account the regularity of the supplies, the characteristics of the product, the intentions of the supplier, etc. In principle, occasional supplies by charities or hobbyists should not be considered as taking place in a business related context."

I would consider GCC or React to fit this definition, while a hobby project like https://github.com/rui314/chibicc not to fit it.

Edit: I don't think you would have any obligations under CRA unless you make a project release available, whether commercially or on Github. The 3-part test I mentioned above only kicks in when there is a release of some sort in the first place.

That roughly tracks with my gut reaction from reading what appears to be the current draft: if you're doing any sort of formalized release process, you're probably at the point where you're doing commercial activity. By the time you're supporting old versions of the software, and cutting new point releases, you're almost definitely in commercial activity land.

Definitely it looks like a higher bar than GitHub is implying--I don't see any indication that merely soliciting donations would qualify for commercial activity.