App store is NOT needed! It is another AOL type of walled garden. There is no reason why PWA can't replace most apps.

There’s even less of a reason to need to ask apple for permission to make my own custom app.

There are more phone users than PC users though. Stats estimate a 4 billion difference. Can you imagine the costs of having just an increase of 400k users flooding your shops and online forums for help because of one of these third party stores/browsers? It makes sense if you could do this in the very beginning (as it was the case for PCs) but for smartphones that were closed since the beginning (it is downhill in the cost/revenue world)

Yes, and it does come with its lot of problems. I've never heard of ransomware attacks on phones, for example.

There are plenty of vulnerabilities for old versions and plenty of people that don't install updates or have out-of-support phones. I need look no further than my immediate family to have multiple examples of both (yes I help them manage this). Yet I've never heard of anyone experiencing negative consequences from not updating a phone. (At least, not beyond some high-profile people that made the news.) Computers, sure. But why not phones? Is the data on there not valuable enough? Too often sync'd to a server?

I don't know but there's something here beyond the ability to install software like you've always been able to do on Android

Does it though? iPhones enjoy a nice isolation model, installing a browser shouldn’t break that.