It's FOSS - https://itsfoss.com/vivaldi-arm-release/
Brief: Vivaldi web browser has released an experimental version for Linux based ARM devices. This means that you can now use it on your Raspberry Pi.
The Vivaldi web browser can now be used on recent models of Raspberry Pi and on other popular single-board devices like ASUS Tinker Board and CubieBoard. It is an experimental build that will work with Linux-based ARM devices. This information was released in a blog post by Ruarí Ødegaard:
“Today, we are thrilled to roll out an experimental build for Linux based ARM devices, including the increasingly popular Raspberry Pi.”