Microsoft has added a new Favourites search feature to Edge Canary.
Previously to search your favourite needed to click the Manage Favourites button and search your favourites in the new page which opened.
The update to Edge Canary 90.0.782.0 brings the ability to search your favourites directly from the favourites pop-up.
Favourites Search can also be accessed by typing Control-Shift-O.
The feature is also an improvement over Bookmark Search in Chrome, which opens a new page which replaces what you are doing. If successful the new feature should roll out to regular users in a few weeks.
Edge Canary can be downloaded from Microsoft here.