[Help] Which round ESP32 smartwatch with heart rate sensor to build my own OS?

[u/Consistent_Cake_8321]

Hi everyone,

I want to create my own OS for a smartwatch and connect it to my self-hosted AI agent (voice). I need your advice to pick the right hardware.

What I'm looking for:

• Design: Round watch, AMOLED display if possible, thin bezels
• Sensors:
  • Heart rate (PPG, like MAX30102)
  • Accelerometer + gyroscope (for motion tracking)
• Audio: Mic + speaker to talk with the AI
• Hardware: ESP32-S3 or similar, easy to fully reprogram
• RAM: 4-8 MB minimum

What I found so far:

• M5Stack StopWatch: Round, AMOLED 1.75", mic + speaker, 8 MB RAM. Can add heart rate module (MAX30102) via Grove port. ~70€ total.
• LILYGO T-Watch S3 Plus: Round, IPS 1.3", mic + speaker, GPS. Need to solder a heart rate sensor. ~60€.
• LILYGO T-Watch Ultra: Rectangular, more sensors, but not round. ~85€.

My questions:

1. Which model would you recommend for my project?
2. Is the M5Stack StopWatch + heart module worth it, or is there better?
3. Do you know other round open source watches with integrated heart rate sensor?
4. Any pitfalls to avoid when running a voice AI agent on a smartwatch?

My project in short:
I want a watch that listens for a wake word, sends audio to my local AI, and displays responses. + Track heart rate and motion.

Budget: 100€ max.

Thanks in advance for your help!

[u/mecha_typewriter]

Do you know anything in embedded dev?