You say this like the scary warnings aren't an entirely artificial barrier by google. Before the app verification, I could install apps from freedroid just fine without any scary warnings.
All Google Android builds show a scary warning before you can install apps outside the system app stores. That's why the judge's ruling required Google to do away with the scary warning, leading to app verification, which accomplishes what the judge required. If you don't use a Google Android build, neither app verification nor the new unknown source installation flow affect you.
Instead, as I pointed out in my original comment, we need to complain about the upcoming "advanced flow" for unknown source app installation. It should not but does require enabling developer mode. It should and does save the user's preferences for unknown source installation across device updates.