This is very cool! I have a similar EcoFlow battery hooked up to a Pixel 4. With Termux this is a very capable tool. I have it on Tailscale (using my own headscale server) and I use it for speech to text and text to speech using the native APIs (which are well supported with Termux's APIs and helper functions). It's a very capable computer. The one thing that I haven't quite figured out is how to run a high-quality wake-word tool.
I initially intended to use it with a ReSpeaker speaker/mic system so that I could use it as a smart home assistant / Q&A bot since Google Home constantly frustrates me with its inability to answer questions that LLMs answer flawlessly but the mic/speaker on the phone is good enough. The only problem is the wake word functionality. I'm going to try Porcupine next and see.