Here is an interesting device capable of recording stereoscopic 3D up to 4:4:4 10 bits, or even uncompressed, and includes a full-fledged computer and monitor. It can all be mounted on the back of a camera. See Portable video recorder computer. Up to 4K 60P 8 or 10-Bit 4:2:0, 4:2:2 or 4:4:4 with true Uncompressed cinema quality, Motion Jpeg, DPX, Prores and HEVC H265. Offer superior quality than VideoDevices PIX-E5, E-7, Atomos Shogun and Convergent Design (http://www.cinemartin.com/next/).

I discovered it by watching this YouTube video by Alister Chapman (though he does not mention 3D in it).

An Introduction To The Cinemartin NEXT. - YouTube