android emulator (i think bluestacks still works), web snapchat client + BetterSnap extension (you can even save the original media file!), on graphene it seems to detect screenshots but not video recording (likely not intentional, there was an open issue to block screenshot detection but no devs were interested iirc)

it's a lost cause except maaaybe provisioning drm keys but even then, as you say, analog hole

re: screen security isn't the same thing - that's what i mean, signal does use those very APIs but not for a half-assed snitching feature

Oh interesting. Yeah, I mean, iOS has the API so it seems silly that they don't do anything about it there, but I guess if you support a diverse userbase like they have to, then user education is impossible and a false sense of security would be a bad thing to give to uaers