The problem is that most normal people (HN is not normal - mostly for the better) don't even understand what sideloading is - let alone actually care.
How can we fix this?
(aside from making people care - apathy enables so many political problems in the current age, but it's such a huge problem that this definitely isn't going to be the impetus to fix it)
I don't think that making "normal" people "care" about sideloading is the answer, because a) it's impossible and b) political change doesn't happen through "normal" people anyway, all political and regulatory change is driven via smaller and motivated groups of people.
The problem is fundamentally that there's a duopoly on mobile OSes that has tons of market power and if they want to dictate a change like "you can no longer install unapproved software," they can just do it.
The solution is to walk away from that duopoly, to suck it up and just stop using their products. We fortunately are able to do this (for now) on desktop and running Linux in 2025 is better than it's ever been, and more people are doing it.
To get Linux or some alternative on phones is a big task, and if you make the switch you're going to lose a lot. But most of what has no desktop equivalent is addictive social media garbage that you should get rid of anyway. The biggest thing I'm concerned about is the state of banking and OTP/2FA.
I think we need to fight for universal electronic access to the financial system as a right without a need for gatekeepers like Apple or Google. In some countries it's already the case that at many businesses you must use your phone to make payments, cash is gone, cards are dying, and you must therefore agree to Apple or Google's rules to use your phone. This is truly how freedom and democracy will die if we allow it. This is way bigger for "normal" people than technical concepts like sideloading. People on the left should inherently understand the importance to liberty of having the right as an individual to buy and sell without some megacorp's permission. For people on the right, well, remember the Bible's "Mark of the beast..."
Secondarily we need to fight for the enforcement of anti-trust laws, which half of HN doesn't seem to even know exist, or feels are in some way unfair, even though they are the cause of these problems. Government needs to reach in and rearrange markets that are dominated by one or two players, it needs to forcefully restructure those companies so that they lose their market power and can no longer force citizens to obey their will. We've done it before, such as ending company towns where you were forced to use the company's scrip at the company's shop to buy living essentials. It's worked, we need to do it again.
The problem is that I want to make calls, SMSes, use WhatsApp and Telegram, Maps and OSMAnd, NewPipe, VLC, Syncthing and a few others on the phone I carry with me.
And to make matters worse I don't want a huge, thick and heavy brick like every Linux phone I read about. I'm on a Samsung A40 now and it's not easy to find a replacement with similar size and weight.
In the country I live in, which is a highly online and highly mobile first country, a sizeable minority of businesses no longer accept cash. A few no longer even accept cards.
At these businesses, there is only one way to pay, which is to pull out your phone, and initiate a transaction through your mobile banking app, you scan a QR from the vendor and approve the transfer.
Mobile banking is so ubiquitous that often these businesses don't even have signage outlining their payment policies, or it's tiny and hard to find.
Some banks do not have an online banking website, the only way to access your money and make a payment is to use the Android or iOS app on an unrooted device, or physically go to a branch or ATM.
You go somewhere, you buy, at the end of your meal or whatever they tell you phone only, no card, no cash.
It's prevalent enough that being outside of your home without an unrooted Google or Apple operating system physically on your person is a significant impediment to buying basic things, like a meal.
Apple and Google will, through a variety of technical changes, seek to make this the case in all of the world, and in some countries they'll succeed. So the important question now is: how will it go down in the next 10 years in your country? How far under their control is your society going to fall?
Banking, money and payments. Limiting those in the name of security is how they will get you on everything else.
They will take away cash and cards and there will only be payment apps, on approved secure OSes which you can't "tamper" with (aka install "unauthorized" software like VLC or a Youtube alternative on), or else the payments apps stop working.
They will take away SMS OTP and there will only be TOTP, because it's more secure. Then they will replace the OTP with a facial scan, because it's more secure, people were being social engineered into giving someone those numbers over the phone, etc.
This is all in process. They don't even hide it, they just say it's for security. It is already happening in countries that are highly online and highly phone-centric.
Note that this is likely illegal, even though I'm sure it's very common in certain places, and arguing about legal tender laws is not how you want to spend every meal of course.
But, in principle, in most countries at least, businesses and private citizens are obligated to accept the country's currency to discharge debts. They're free to have an upfront no cash policy, and refuse to do business with you if you try to pay with cash, for example making you leave all your groceries at the checkout counter. But if they claim that you have a debt to them, such as a meal you've already eaten and now must pay for, they must accept any form of the country's currency, such as cash, as a means of you paying that debt off.