MKI2C is an open-source standard for hotswap i2c, 3.3v modules on compatible keyboards.
Prices are TBD, to be finalized before Sol 3 group buy start.
Each module can be installed to the keyboard using screws and requires no soldering. OLED Modules use white panels. Touchbar modules take up 4 keys, and provide 3 touch buttons with swipe up/down input for 5 total QMK-configurable commands.
RGBKB's Sol3 and Zygomorph 2 support MKI2C in certain positions.