I‘d love to see such a device based on Android with 5 years update guarantee. Users could easily use it for any of your envisioned use cases and you could focus on your hardware competency
Android will never work in a cordless scenario. We have device with 3 months autonomy and the next gen device currently nearing production drastically increases that as well. We've evaluated everything embedded, especially Android (love the ecosystem), but there is literary no tech that would give you full operation and full wifi connectivity, months of autonomy off a standard phone battery and Android. We had to develop a lot of proprietary stuff...