Hi,
I have 10+ years of experience in embedded design and development. I have expertise in firmware development on various platforms.
I have already worked on MCP2221 linux driver for raspberry pi and I am damn sure I can also make it compatible with Ubuntu.
MCP2221 couldn't be connected directly as it must be connected to USB - I2C bridge. If you such arrangement , you can use MCP2221 for ubuntu.
Let me know if I can help you.