Now that most browsers share the same Chromium base (yay monopolies!), there's potential for some synergy between them. One step in that direction could be sharing tabs between different browsers, according to a flag that recently appeared in Chrome Canary.

Chrome Story originally spotted the #mix-browser-type-tabs flag, which has the description, "Allows tabs to be dragged between any browsers that support tabs, including apps." The feature is marked as compatible with Mac, Windows, Linux, and Chrome OS Android doesn't get to join the party, at least for now.

Annoyingly, details about this are scarce, even in the feature's tracker. It seems like this will allow tabs to be dragged between Chrome and any browser (or other application), and vice versa. One comment from a Chromium developer notes that the other browser/app has to add support for this functionality, it won't magically work:

Currently we disallow dropping tabs onto a browser that does not support FEATURE_TABSTRIP. This adds an extra check to also disallow if the source and target browser are not the same type (APP vs NORMAL).

The feature doesn't seem to be functional at the moment, either. I installed Chrome Canary and a nightly build of Chromium and enabled the flag on both browsers, but I was unable to drag tabs between the two. I also downloaded the latest Canary build of the new Microsoft Edge, but it doesn't even have the flag yet.

The tracker for the feature also reveals that this is on track for Chrome 80, which is scheduled to arrive in February 2020. Hopefully it will become functional soon⁠ ⁠— it could make copying data across browsers (and other apps) much easier.