There are two varieties of this tuner (at least?) If lsusb reports 0572:c688 it is version 2 with the silicon labs chip as reported above. The necessary drivers are in the v4l media_build git and I’ve just finished building them in with the instructions here and here. Not a quick process but it seems to be successful.
The tuner is now showing up in tvheadend but I can’t figure out how to get it to scan for channels. It was simple on Linux Mint and openelec on the Pi but OSMC doesn’t seem to find the dvb scan files - where are they?