tl;dr both are artificial limitations by Apple, not technological problems to solve.
I know about the VoIP workaround; however, I haven't found a reliable VoIP service without having additional costs where I live. If the cellular iPad Mini 5G could also be a "regular phone," as many cellular Android-based tablets can be when you simply put in an (e)SIM that would solve the issue hardware-wise. From the side of cellular providers and eSIM offerings, it would be possible where I live, unlike probably where you live.
I receive few and make even fewer cellular phone calls - low single digits each month - but I do require it being still possible/available. Unfortunately I also still get plenty of regular cellular text messages 2FA codes from services that don't offer alternatives ways (authenticator apps, email etc.) and they do not have competitor services I could switch too. I know this is a very niche use case however. Hope it becomes possible with a future version.
As for being able to just install Apps from anywhere if I choose to do so - it's simply down to having the user choice option and not being artificially limited by Apple. They do this, to protect their lucrative App store cut / core technology fee from alt-stores. There is simply no other reason why it can't be done like on MacOS (and all other major OSes).
One thing I'd love to have is a real alternate browser that runs on a different engine - simply to have the choice when there is a webkit security issue for example - or that allows different kinds of add-ons.
Currently, Apple makes it artificially difficult - by limiting not only the distribution, but even the building and testing geographically. Thus even the big players like Google (Chrome), other Chromium based ones like Microsoft Edge, Brave etc. (all with Blink) or Mozilla Firefox (Gecko) haven't been able to viably offer a real alternate Browser, since the costs to develop two iOS/iPadOS browsers in parallel are obviously higher, an inefficient way of resources and the possible user base is limited.
That’s absolutely a cellular carrier thing. Why would Apple take all of time to build such a niche functionality there are likely few and far between who ware for, when cellular companies wouldn’t even use it in their primary market? Makes zero sense…
App sideloading would open major security holes in the platform. Yes, macOS supports it, but macOS isn’t the same system and isn’t A. Built on the same security platform, B. Doesn’t typically house as much private data as an iPhone or iPad, and C. Is often the first computer used by children (who are far less wise about what they install from where, and would be easy targets for fraud).
Just because the Mac is stuck with a legacy system that’s less secure and less convenient for users (for example, many developers force us to have to sideload their app on the Mac, opening us up to more risk of installing malware, and then every different app has its own different way of managing app updates which sucks), doesn’t mean that every modern system needs to continue to work that way. App stores are clearly better on multiple fronts for consumers, and this is why virtually every platform out there offers one… They provide users with a secure place to install software, and manage software updates from. They also make it far simpler to find apps in the first place.
And consumers aren’t the only ones that win with the App Store model, small developers benefit too. It’s far more financially viable for small developers to make use of the App Store with the cheap commissions then pay to host their own website for their app, pay for payment processing services, and advertising for their app. It’s a win win.
The App Store model clearly seems to be very popular because of the many benefits it provides to customers
and developers. I see no reason why we should take a step backward and regress back to a system that’s far less convenient and intuitive for customers, and puts customers at a pretty high risk of fraud and malware, and is far less convenient.
As to alternate browser engines, this would likely also poke holes in the system security. If they can implement it in an extremely secure way, then fine, I wouldn’t have any problem with that, but I think there would be a lot that would go into that.
