My first choice of MCU is ESP32-S3. It offers a good amount of flexibility and covers all the requirements I want for this project:

• (Must have) minimum 8 ADC input. Performance of ADC is slightly poorer comparing to Teensy 3.2 and the final decision hangs on the test to ensure that data is sufficient to run the algorithm developed on Teensy
• (Must have) I2C bus to drive a screen, used to configure the mouse settings
• (Must have) Few free output pins to drive few FETs, and addressable LEDs, this thing needs some bling
• (Must have) At least 6 free input pins used to connect the buttons. Since this is a mouse targeting CAD usage, having some buttons to emulate keyboard keys is a must (e.g. ESC, Enter, ...)
• (Must to have) One of:
  • USB that supports HID device, emulating keyboard & mouse
  • BLE that supports HID device, emulating keyboard & mouse   <--- Preferably BLE, it would be cool to make this a wireless mouse

With this in mind, the priority is to validate the feasibility of ESP32-S3, although I don't have any big concerns at the moment, it looks to live up to spec above.

On the side, I've also been playing with drafting some design ideas, trying my hand at designing something nice. It's probably the first time I'm trying to make something somewhat "visually appealing", and not just a square box 😂

The funky looking "spoiler" on top is meant to house around 5 programmable buttons, and the hole on top of the knob will likely have 2 buttons as well. Cutout in front is where the screen sits.

Electronics

On the electronics side, I'm hoping to get the device to be wireless, which the requires a battery and a charger. Old phone battery I have lying around should provide enough juice for a couple of hours of continuous runtime, and paired with something like TP4056, it can get charged while the device is plugged in.