I used the instructions above to install it with apt install and the full path and it is working great. I was missing the full path for the install. Is it possible that the wrong vivaldi file is downloaded? What are the computer specs and which devuan excalibur download, example live usb or fully installed, which desktop are you using? If you can't uninstall there should still be some way to delete the file from your system. The more information you can detail about the setup. the better someone here can help you. Vivaldi does occasionally freeze on my son's windows laptop when we use it to watch tv and it takes xing out sometimes a couple of times or occasionally a restart to get vivaldi to behave so there is the possibility that there is a vivaldi glitch even though it usually works smoothly. (or the windows 10 on my son's laptop is having seizures,we don't really know...)

I think I see what I missed.

Installing Vivaldi via the terminal
After downloading a suitable package for your distro, you can use the following commands (from the directory where you saved Vivaldi) to install one of our Linux packages directly from the terminal [where ‘vivaldi*‘ equals the name of the Vivaldi install package].

Ubuntu/Debian based distros:
sudo apt-get -y install ./vivaldi*.deb

This part:(from the directory where you saved Vivaldi)
Unfortunately I'm not sure what they mean by this.