Aside from the project itself: They are eusing a "Polyform License" I haven't encountered that before. So it's not "open source" as many people might expect from GitHub and Polyform licenses seem to inherit the "what exactly is the boundary between non-commercial and commercial" issue as do CC licenses.
I use CC for most of my "work", and it's pretty clear to me what "commercial" means. If someone uses my work to earn any money, then it's commercial. Unless they contact me and explain why it isn't, then i can grant them a license that allows them that.
This is only relevant if the CC is CC-NC, otherwise commercial use is "ok". it's pretty straightforward.
> If someone uses my work to earn any money, then it's commercial.
it really is that simple. It's meant for creative works, but not just; if i make a song and license it CC-NC, you can't use it in a video if that video gets ad revenue, patreon, snail-mail donations.
> Meaning "done for the sake of financial profit" (of art, etc.), "prepared for the market or as an article of trade" is from 1871.
It is trivial, unless you are looking for loopholes to get around licensing.
This is only relevant if the CC is CC-NC, otherwise commercial use is "ok". it's pretty straightforward.