It's not limited to Google. For example, this TI mmWave sensor (
http://www.ti.com/product/IWR6843) has an associated reference design for gesture control (
http://www.ti.com/tool/TIDEP-01013).
(Disclaimer: I've never actually used that chip or reference design and have no idea how well it actually works in practice. I just think it's really neat that mmWave radar chips are readily available at very affordable price points.)