It does replace system webview.
Both Vanadium and Mulch are powerful. Mulch is Divest os default vebview and is using Vanadium patches. While the Vanadium is Graphene one.
https://gitlab.com/divested-mobile/mulch
https://github.com/GrapheneOS/Vanadium
I stick with Mulch, because I added divest repo to Droidify, so I can upgrade webview as soon new update comes out. No need to wait for module update.
Haven’t found a good way to easily update Vanadium. On XDA module’s thread you can read about it.
https://xdaforums.com/t/magisk-module-webview-open-webview-2-3-1.4496119/
Music scrobbling solves that issue for me. Navidrome integrates well with for example last.fm. Despite having my music listening history there one can find recommendations based on their music taste