Family Link not available on OnePlus One? My son is using an old OnePlus One, and I wanted to install Google's family link on it. The browser finds it but the play store doesn't, and when I click it in the browser (and go into the play store) I get a message "Item not found".

Because the OnePlus One's software has not been upgraded for ages I tried to solve it by installing Lineage OS together with the play store (via OpenGapps nano) but for family link I still get the same message.

Is this a software issue that can be resolved? Or is family link not supported for all handsets (including the OnePlus One)?
As per https://families.google.com/familylink/device-compatibility/ the child version of Google Family link requires mostly Android Version 7.0 and newer, with a few exceptions.