Let me just upgrade my Vivaldi browser.
I am using Ubuntu here, so of course I download the rpm. On double clicking it from the download panel it launches into an ncurses based installer that looks like it is straight from DOS, no authentication password is asked for. It defaults to the install location `~/Vivaldi-Builds/stable`. After it is done I just restart Vivaldi and there you go, new version. Easy!
For those of you running Windows or macOS, this is the normal install method for all software on Linux. π