Click the Firefox menu (three horizontal bars) in the in the upper-right corner of the Firefox window and click Library. Then, click Synced Tabs. All tabs open on all active, connected devices are listed on the Synced Tabs menu. Click the web page you want to open from another device.
How do I share all tabs in Firefox?
Share multiple tabs
Tap the three-dot menu button in the tabs tray. Select Share all tabs. The list of tabs to be shared will appear.
Does Firefox Sync across devices?
Firefox Sync lets you synchronize bookmarks, add-ons, browsing history and other information across multiple devices.