▲ ▼ Browser tab group sync between PC and the mobile
Tab groups are a major productivity feature in modern browsers, If not available by default there are add-ons which enable them. This allows us to group various tabs in the browser to avoid clutter and easy access.
Although individual websites are synced between PC and the mobile using a common account the tab groups aren't synced. So same level of productivity is not available on mobile browsers.
Since Firefox mobile has started to allow add-ons and that it's available on the desktop as well I think the best bet is to develop an add-on for both platforms which provide tab-group sync.