You said there are a “few” choices. Then you with your own free will are perfectly capable of buying one of those few devices are you not?
There is very much a choice of homebrew applications - buy one of the “few” devices you admitted existed and develop for it.
You could even buy one of the Linux phones.
> So sure, you personally may be able to buy development boards specifically but when you can't get your software to the average person's device, what does that mean for adding competition to the market?
The “average” person decided that they didn’t care about obtaining homebrew applications enough to buy such a device.
> I'd much rather live in a world where being more open means there might be some malware lurking as opposed to one where everything is so locked down that I am at the mercy of what these large corporations deem acceptable for me to do on hardware that I "own" in the name of safety and security.
And you are free to make that trade off and buy such a device.