Vivaldi might become my default browser if it were not for system integration. I have a Mac, a Macbook, an iPad and an iPhone and I do rely on reusing windows opened somewhere else, and storing passwords in a common store (with finger crossed).
I'd love to see this as well. It especially triggers the hell out of me that Chrome, Vivaldi, Opera won't use keychain which every other app on OSX uses.
I would also like to see this -