They just wouldn’t happen in the US, legally
They do happen. Though relatively rarely, compared to other countries.
I say nationalization because no US company is going to agree to the severe punitive ”regulation” examples you’ve provided. And, the only way to force them to happen anyway (for US companies, at least) is for the government to take over the company.
It still doesn't need to be nationalised. Antitrust rulings or legislation is is enough.
Standard Oil was broken up without the government nationalising the businesses. So was the Bell System. Intercarrier rates have been regulated by the FCC without nationalising the Telcos. The state of California regulates private companies' electricity rates through it
Public Utilities Commission (yeah... that didn't always seem to work so well for the state and its electricity grid, did it?).
One thing we can definitely agree on: The company isn't going to take accept any such measure without doing their utmost in fighting it. Also, discoupling the App Store from the hardware manufacturing may be "difficult" (but then, maybe desirable for other government "agencies").
For example, depending specifically on what you’re asking for (say, Apple takes 0% cut on AppStore charging?), that is defining a condition where Apple could argue that they wouldn’t be able to continue to operate
I'm not advocating for anything specific. And a 0% cut would would obviously make them lose money on operation of the App Store itself. But would they shout it down? Unlikely, considering they're making huge money from hardware sales.
On the other hand, the App Store itself technically very little "service" for subscription-based services like Netflix. Especially compared to the 15% or 30% tax of all subscription revenue. Apple doesn't do much more than hosting a few MB to distribute an App downloads. All the heavy lifting of the streaming is done on Netflix's servers.
Does Apple provide developer tools? They do. Though you could argue that do the same for any developer that wants to distribute his app for free - and they recuperate their investments from hardware sales.
I TOTALLY understand why your credit card and your bank accounts require smartphones
So I've opened a couple of bank accounts online, do the ID check through an app. In some cases this was the only way to do it.
What's preventing Apple from charging 15% or 30% of my monthly bank account fees - going by the same or very similar logic they've tried to apply to gaming or streaming services?
I signed up into the banking service through an app from the App Store. And the bank is making money of my "subscription" to such services.
In the end, I believe, there's almost a de facto duopoly (in the US) for mobile app download platforms.
With estimated (though disputed) operating
margins above 70% and indications for Apple leveraging their market power, they will be increasingly scrutinised by governments and regulators.
They better manage a fine line operating as a neutral platform provider charging "reasonable" fees - or shouldn't wonder if they get sanctioned.