The Sea-Micro is a fully open source Pro Micro alternative that replaces the Micro-USB connector with a USB-C connector.
We have attempted to keep the cost of the controller as low as possible, while still retaining the follow key features:
It has been tested on a wide range of split/DIY keyboards including: The Sofle, Corne, Helix, Contra, Revuing, Milk 2%. For split keyboard applications, it is possible to use the sea-micro as the master and your conventional pro-micro as the slave.
The Sea-micro was developed by customkbd and JoshJoshua and is an open source project. Please find source files on Josh's github respository here.
See a review of the sea-micro from Don (The Board Podcast) below: