I kinda wanna make the Arc sidebar (the best bits IMO) but as a macOS menu-bar app? Essentially it would be your bookmarks in the #macOS menu bar and it would just open up in your current default browser and you edit in-place. How hard could it be?
It would also be important to have an interoperable format for the bookmarks. My bookmarks are already currently stuck within Arc so I wouldn't want that to happen again.
It might also be cool if it could be a browser extension too? So maybe it be a #PWA that you could also set as your homepage. Maybe I'm feature creeping too much already.