the right answer is to deliver a usable SECOND device which happens to be linux based, and which has serves a purpose. Then over time, apps get ported.
realistically, this device would need to tiny to justify the extra weight, device-to-keep-charged, etc.
one idea: make it wifi-only and tether from your primary mobile device. This skips all the carrier nonsense, to focus entirely on the core use case(s).