You can, part of the script corresponding to its UI is proprietary, but UI code is written in plain, accessible code for those who read HTML, CSS and JS and even moddeable by the user, but can’t be forked legally by Chrome or EDGE (🖕) nor by other browsers. It`s something like open proprietary freeware. There are no logs, tracking or any other crap. nor third party investors. Sync ee2e no-knowledge. The rest is OpenSource with several different licenses, specificated in the source package. As all other browser, collecting anonym statistical data (country for lenguage settings, OS, needed tecnical data)

https://vivaldi.com/source/