I agree that this is a horrible step in the wrong direction but in terms of the solution I have a different take.
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.