Yes - it would be great to learn how to enable the capability. I'm trying to build a chromium kiosk for my kids at home using a raspberry Pi and since there are no armhf builds of "Chrome" and only Chromium, i'd like to find a way to support the family link capabilities to allow them to use Docs, Sheets, etc. Totally cool with restricting web browsing completely.
My understanding (deduction) is that since chromium is open source and "fungable" compared to official Chrome builds, Family Link is not supported to restrict any liability or nefarious actors. That said, I appreciate the thought on that, but more than happy to have it as an opt in capability and sign a waiver on chromium if that is the concern.