Emotional talk aside, there's not many good solution to this problem, unless of course F-Droid starts to make their own phones.
But then, Librem 5 Phone was just failed few years ago, telling the story that people who care about their rights are still sensitive to how much they would pay (which is a form of rights too).
Also but, there is the thing, making a phone is not easy. If you reach deep enough, you'll eventually reach the layer where you realize how solid the monopolization has become. The global telecom standards if you read them is in the hands of few companies, Boardcom, Motorola, Huawei, Nokia and such. They'll control whether or not your phone can access the network. Then there's telecom companies who runs the network, and they might have to approve your device/modem as well since they got their channel allocation from the government.
It's not easy, and it's not just the software problem.
Oh and yes, we also have the software problem. Linux, if you want to go that route, cannot be used as a mobile OS, as least not for the public, because the average people don't know how to properly secure their system, and Linux is not a restrictive-by-default system. It will be a malware nightmare if you ship Linux on a phone as is.
The best hope for now I think is for geek vendors to make more mobile/4/5G enabled Fairphone or uConsole-like product to the enthusiast market, and then you can load whatever OS on it as you want.