Hyperpixel 4 touch i2c button question & more

I’m working on a talking camera project that will use tesseract ocr and mimic 3 tts. the idea is to create a DIY assistive tech device for my daughter who is dyslexic so that she could use it to take pictures of book pages or newspaper articles that she has trouble reading and have the camera read out the text.

I have a raspberry pi 4 4gb model and the hyperpixel 4 touch (rectangular). I am working on designing a 3d printed case similar to the pikon case which will house a 5000mah battery. I’m trying to figure out if I can use the i2c connector on the back of the hyperpixel to connect an i2c button like the dfrobot gravity button (Gravity: I2C RGB LED Colorful Button Module - DFRobot) as a shutter button for the camera . I also want to have a small speaker that can be installed inside the device. bluetooth speaker is not an option. I am interested in using the max98306 amp to drive small speakers. Not sure how the max98306 would be connected, considering hyperpixel’s usage of all gpio ports, but there is a thread here where someone suggests they have done it successfully, without specifying the details: Hyperpixel 4.0 sound? - #3 by fireslayer26.

Also would be interested in whether it would be possible to use a momentary button to power on / off the Pi, could I just run trace wireless off the gpio pins before fitting on the Hyperpixel, or would that cause problems?

The Hyperpixel breaks out (software) I2C, but for the button you want to use, that should be no problem. DFRobot does not link to a Linux or Python driver, so you are on your own (but maybe someone already solved the problem).

Powering the Pi on or off is theoretically possible. The problem is how to do a clean shutdown. If your talking camera does not save state, it would be possible to set it up as a ram-only device and then you can just turn it off without a clean shutdown.

Have you ever thought to put the controls (e.g. button) on a MCU (like the pico-w) and use wlan to control the Pi4?

Regarding sound: I would skip the max98306 or any other amp. There are many cheap and compact speakers available that have 3.5mm line-in plugs which you just have to connect to the plug on the Pi4.