As for the requirements, I will take your word for it. And I do appreciate that you put the emphasis on security as it is often overlooked. I guess what I'm saying is that having control over my phone (as opposed to BigTech or apps having the control) is for me a much higher priority goal than just security by itself. Hardware reparability is (again, for me) a close second.
Anyway, I hope you find a good partner for the phones, and I'm curious to see what you come up with!
Is this really that big of an issue? It's like a couple dollar fee every 4-5 years or so.