Works great.
Only thing missing is the ability to search all open windows.

Loving it, it's a great companion to the "Multi-account Containers" --- at this point April 2021, you can't search tabs that are not in the same container as the tab you are searching from inside of the URL bar.

This provides an elegant and fast way for you to search all of your tabs.

I only have 1 gripe in 2 forms -- the Tabby extension button _has_ to take up space in my toolbar:
- if you put it in the overflow menu the Tabby UI breaks because it doesn't "know" how wide to be
- if you "remove" it from your toolbar, and use the shortcut keys, the Tabby UI doesn't not show up, but still seems to function when you type anything and hit enter

I was thinking of building something like this, but great to see someone beat me to the punch.

Nice work @JulianWels