> Are there any other Operating Systems than iOS, Android or Android flavors
Yes, there are many more: GNU/Linux, Windows, macOS, *BSD, etc.
This will prevent people who only own a computer and not a modern iOS/Android smartphone from accessing services and platforms.
This also sets a very strong anti-competition pressure. Which company will try now to invest on developing a new OS for smartphones if we already know users will not be able to access the most popular services & platforms with it?
Well, that would boost up torrent and sites and places like Usenet and IRC with no age verification at all. English speakers can just use overseas servers (or non-UE services such as the ones in Switzerland). And maybe Usenet servers outside the US too.
Spanish speakers in Spain will just register services in Latinamerica sites with a VPN. Despite the dialect differences, non-jargon Spanish it's understood everywhere and once they got their user registered they can switch the country anytime.
Distros like Trisquel will just set their sites and mirrors outside the EU. And, well, if they provide a portable torrent client for Windows among the torrent the law would be utterly broken.