The open source UnaWatch can be disassembled with one screwdriver, with user-replacable parts.

https://unawatch.com/

- Ultra low power cortex M-33 CPU
- 2.5MB RAM
- 4.3GB storage
- Bluetooth LE 5.2
- Haptic vibration
- Piezo alert
- Altimeter
- Temperature sensor
- 280mAh hard shell battery
- 1.2" 240x240px LCD with backlight
- Dual frequency GPS
- Heart rate monitoring
- Peripheral oxygen saturation