I came to share basically the same idea. I know there are extensions but I want some kind of workspace/session support built in so the browser can do stuff like cache tabs in a workspace so I can load a workspace and resume instantly. Switching workspaces should be quick with maybe a UI like ctrl p in sublime text or VsCode or even like the gnome dash. I would pay for a license to use a browser that focuses on being a productivity tool with features like this.