Android is a solid basis for a homegrown solution. We just never had the need to build one just yet. What Google and Apple built was convenient. But it's not as irreplaceable as some might think.
That is not a problem of Android but of the hardware and funnily enough much of that is not produced in the US. I think we could cobble together a working phone in a short time and iterate upon that if it is necessary. Hardware has advanced sufficiently that we don't need the latest greatest to have an okay experience.
Debatable
Android is a solid basis for a homegrown solution. We just never had the need to build one just yet. What Google and Apple built was convenient. But it's not as irreplaceable as some might think.