It's forcing all OSs to do something that only a few should be doing. The correct way to do this is for the interested parties to form an association that does four things.
1. Creates a protocol with desired signals (country and a variable list of whatever others i.e. age,state) that clients (including browsers) CAN choose to use and forward.
2. Create an api OSs CAN implement to inform clients of those signals and if they can be overidden in the client. (Possibly even create an OS or service to run on OSs that implements it, parents can choose to install specific OS or service)
3. A open source server for governments to specify common classes of content and what to do when a specific SIGNAL (from the protocol in 1) is recieved (Serve content to SIGNAL group/serve content to everyone/never serve content). And what to do if content isn't in a class it recognizes(Serve content/not serve content). Association could also be extend it's duties to coordinate a list of types of content.
4. Maintain an authoritative list of servers by country so that those hosting services can reach the servers hosted in 3. So that webservers can visit those servers to find what they can serve if they wish to apply the law for that jurisdiction.
Horrible because it does codify less freedom and censorship. The advantages are that for a jurisdiction liability can fall on the right actor.
If you run a website/app you worry only if your in a jurisdiction that mandates you use the protocol and can easily geoblock crazy countries by using that signal and choose if a jurisdiction you want to deal with is worth the effort of coding for or whether you want to ignore that countries laws.
If you are a user you can choose to install the API or use an OS that implements it or an OS that spoofs it with only the liability of your jurisdiction. If you are a parent you can use an OS(or install a service) to implement it on your kids accounts.
If your an OS developer you can add functionality if desired/appropriate.
If you are a country you can specify what signals you use/require and can specify required signals (i.e. US may request the State signal so it can decide if it needs other signals to evaluate whether to serve "Social Media" content (i.e. age in the case of state=california)).
Not perfect but actually keeps punishment/enforcement to appropriate jurisdiction and means you can actually gracefully avoid liability for sites in broken jurisdictions rather than either kowtowing or being in breach. Also means it can be implemented in client if you don't want it on your OS or want the convenience of not being asked age without the ridiculous other stuff.