This is a project which can convert an USB Keyboard to BLE Keyboard. It's based on CH32V208 from WCH.
You can find the introduction of CH32V208 here https://www.wch.cn/products/CH32V208.html. It has 2 USB controller one is USB device only, the other can be an USB device or host.
I make this by lceda you can also find the sch&bcb designed here.
My homepage is: http://www.lab-z.com