" It applies to operating systems that work with associated app stores on general purpose computers or mobile phones or game consoles. That’s it"
Everything is a general purpose computer. Just look at how many things have been made to run doom. I haven't read the law specifically but if it actually does say this then that language is useless and means practically everything.
vague laws are put in place so that they can be used selectively to punish particular victims while letting friends through the nets
Wood is edible when processed correctly, but it's not legally considered "food" because there are a bunch of nontrivial steps to get it into that state. Likewise, any reasonable interpretation of "general purpose computer" in this context by a judge would not include your microwave oven just because someone with skill and finesse could transform it into a cursed Doom arcade machine.
Laws are interpreted by people trained to fill in the blanks[1] with a best guess of the legislative body's intent. And the intent here seems pretty clear: to regulate computing devices that let end users easily install software from a centralized catalog.
[1] which we all do subconsciously in day-to-day speech, because all language is ultimately subjective