This is a note attached to every Vanadium release on GitHub:
"This update is available to GrapheneOS users via our app repository and will also be bundled into the next OS release. Vanadium isn't yet officially available for users outside GrapheneOS, although we plan to do that eventually. It won't be able to provide the WebView outside GrapheneOS and will have missing hardening and other features."
So, as said earlier, Brave may be your best alternative.