Vanadium and app do not show current location in Pixel 8a

Sparks

We use the site drgl.nl on Vanadium which shows actual departure times at nearby public transport stops in The Netherlands. When opened for the first time, it asks for location rights which I allowed for every use of the website. On my Pixel 6a and Pixel 8a of my son it works smoothly: the website in Vanadium finds the nearby stops. However, on the Pixel 8a of my wife, the current location search seems not work at all, despite having the location rights set correctly
The same applies to the Dutch railway app NS: it does not show the current location.
The navigation app CoMaps can find the current location, so the gps sensor or something like that on my wife's phone is not broken. CoMaps seems the only app which has used the location rights, according to Location privacy configurations of the phone.
How can I set the Pixel 8a of my wife so that Vanadium and the NS app can use current location?

Sparks

I just found the solution: just simply enable "Reroute location requests to the OS" (within Settings -> Apps -> Sandboxed Google Play). Now the Dutch website drgl.nl shows the nearby public transport stops based on current location.

It still leaves me with a question: why has the settings of Sandboxed Google Play influence on showing the current location within Vanadium? Vanadium is not linked with Google Play? I don´t know exactly what the rerouting location requests function does. I presume the website asks for Google Play location, but Pixel 8a is set to GrapheneOS as location service. With the rerouting enabled, the website uses in fact GrapheneOS location service instead of Google location service.
It could also explain why the CoMaps app still shows current location while the NS app didn´t. The first is downloaded from Obtainium, the latter from Google Play. Since the rerouting location is enabled, the NS app now shows current location.

Please correct me if I'm wrong.