Partly. It mostly works well for the things I use it (push messages, maps, exposure notifications seem to work too). Some apps behave a bit weirdly if the try to access specific API's, like Google Pay. So it definitely isn't fully functional, but works well enough for many use cases. There is also a LineageOS+microG fork, which makes trying it out a lot easier.
The way it works is that it pretends to be Google Play Services, so it isn't transparent to the apps. Not sure if the apps could figure it out it isn't running on the real deal.
I'd be curious about a legal opinion, but as far as I understand it, the restrictions would only apply to actual commercial products. But he isn't actually selling the cheese as far as I know (only selling a video how to make the cheese).
The author should write a similar article about himself, because the whole article is filled with dubious claims and misguided evidence. The two main claims are "Since the GI is a measure of how much of a negative response your body has to certain sugars" and "research showing harms from canola oil". Neither can be ascertained. A big problem with nutritional science is that it's complex, therefore it is neigh impossible to discover the truth how specific foods really impact the body. I'm also of the opinion that the term "healthy" shouldn't be really used. Here I go with Paracelsus: "All things are poison, and nothing is without poison; the dosage alone makes it so a thing is not a poison."
The author invites us to his newsletter "on getting healthy, wealthy, and wise." Yeah, it's all a baseless marketing ploy by, and for, the author.
I want to note, I'm making no argument that Oatly should be considered healthy though.
According to statcounter, Germany has the highest usage of Firefox and fourth highest usage of Linux (behind Ireland, Greece and Luxembourg) among European and North American countries. Additionally, you have the Chaos Computer Club, which is somewhat prominent and could influence the thinking about FOSS.
The way it works is that it pretends to be Google Play Services, so it isn't transparent to the apps. Not sure if the apps could figure it out it isn't running on the real deal.