Vivaldi has proprietary components that the developers will not disclose due to chronic fears of “corporate espionage”

Thus Vivaldi cannot be planted in a build farm nor be compiled yourself, so you have to take their precompiled binary and deal with it.

Stop being scared and use Librewolf and keep ungoogled chromium in the back for compatibility (and terrible nonfree “webapps”).

Nonfree browsers are a waste of everyones time.