Arduino Core for SAMD9,10,11 available?

Is anyone aware of an Arduino core that supports raw SAMD09, 10, or 11 MCUs ?

There is GitHub - mattairtech/ArduinoCore-samd: This is a fork from arduino/ArduinoCore-samd on GitHub. This will be used to maintain Arduino support for SAM D|L|C (M0+ and M4F) boards including the MattairTech Xeno Mini and the MT-D21E (see It adds support for new devices like the D51, L21, C21, and D11. It also adds new clock sources, like a high speed crystal or internal oscillator. that includes samd11.
Seems to work, but it is very much not optimized for the smaller chip