AI-powered scientific calculator build – need advice

Hey! Engineering student here. For a uni project I need to build something original, and I want to make a physical calculator that connects to the internet and uses an AI API to solve complex problems (integrals, equations, unit conversions, etc.).

I have two broken devices I could salvage:

- Xiaomi Poco X5 – dead screen but fully functional (SIM, WiFi, camera all alive)

- Casio fx-991 CW – cracked/broken, but keyboard matrix might still work

I'm considering a few approaches:

- Option A: Strip the Poco X5, fit internals into a custom enclosure, wire Casio keyboard via Arduino Pro Micro as HID

- Option B: Skip salvaging and just buy a fresh **Raspberry Pi Zero 2W**, fit it inside the Casio shell, wire the keyboard matrix to GPIO, add a small SPI display, connect via phone hotspot

- Option B+: Same as B but add a SIM7600 module for standalone internet

I'm leaning towards the clean Pi Zero build since salvaging the Poco internals seems painful. Main concern: Pi runs Linux, not Android – is that a big barrier? I know Python but not much embedded Linux. Would a simple Python script calling an AI API be realistic?

Also open to completely different platforms – ESP32? Orange Pi? Anything simpler?

Questions:

1. Fresh Pi Zero vs salvaging Poco X5 – which would you go with?

2. Is Linux on Pi a barrier or is Python enough?

3. Has anyone mapped the Casio fx-991 CW keyboard matrix?

4. Best small display for a calculator form factor?

5. Any other ideas or approaches?

Thanks!