Well, "somehow", Android phones are sold in these countries, and while Android devices are not truly "open" by any respects, they almost always are able to let you "sideload" absolutely any sandboxed app you want... including these apps that are banned in all of these countries that Apple insists they are forced to block. The reality is that Apple is only forced to block them because they have decided to be a centralized arbiter of all content for these devices, something that Google and Samsung did not do, and so have created a powerful, centralized bottleneck that can be leveraged as a tool for regimes to control their population. The only reason this is thereby happening is because of Apple's greed: they would rather be able to collect 30% of every transaction that occurs on their systems than to add a trivial feature--sideloading--that would fight against and undermine this oppression.
I highly recommend watching a talk I was giving a few years back--the best version being when I did it at Mozilla Privacy Lab (link below)--which focuses on the ramifications of the core of this problem across the industry (but of course, with one of the narrative focuses being on Apple, as I have a lot of background knowledge there).
There has been speculation that Google will eventually make its Advanced Protection model, currently optional, mandatory in a future Android version. A consequence of that will be that sideloading will only be possible if you connect to the phone over ADB and install the app from the command line that way. Obviously only a tiny, tiny amount of techies like us will every know how to do that. So, I don't think Google can so easily be held up as an example of user freedom.
You don't particularly have to learn to "use the shell", however. If you only want to sideload apps it's just a matter of copying simple commands from the internet. This is well within the capabilities of most people who are technically competent enough to sideload apps now.
Users are certainly very reluctant to drop into a command line, but in my experience if it is a true necessity for something they want to do, they don't actually have that much difficulty with it.
No, the vast majority of Android phone owners are not going to open the command line. The very prospect of it will daunt them, or it may even be unfamiliar to them (a lot of Android users, especially in the developing world, rarely or never use a traditional computer and are unfamiliar with the full range of its features). Even those users who would copy and paste into the terminal are a niche more comparable to us here than the average phone owner.
Yes, of course sideloading may still remain possible in such a scenario, but it would not be mainstream enough to sustain any kind of mainstream ecosystem of apps outside of the Google Play Store. Even F-Droid supporters have been worried that clamping down on sideloading could marginalize F-Droid even further than it already is.
The vast majority of Android users are also not going to sideload illegal apps currently.
Don't get me wrong, I agree that trying to restrict users from installing software of their choice on their own computing device is user-hostile, but in this specific scenario, users sideloading apps banned by their government, I don't think having to open a command line to do it would significantly shrink that userbase, which is already comprised of a small minority of particularly committed people.
But all of this is moot regardless, because AFAIK this doesn't extend beyond the realm of speculation.
Safari does not block a user from visiting dating websites, this is true even if a dating website is illegal for the user to access. Repressive police states do not limit themselves to only targeting people using dating applications versus dating websites.
If you pay them money, Apple has/will let you make virtually any data siphoning and user-hostile application you want, and they will allow you to sideload it without review (enterprise program). The common factor is control that benefits Apple.
I highly recommend watching a talk I was giving a few years back--the best version being when I did it at Mozilla Privacy Lab (link below)--which focuses on the ramifications of the core of this problem across the industry (but of course, with one of the narrative focuses being on Apple, as I have a lot of background knowledge there).
https://www.youtube.com/watch?v=vsazo-Gs7ms