NetRunner88
I dont see the reason for that app
Just open Vanadium, open maps.google.com and install as webapp
This is not the most secure and private option. You trust google to not run malware on your device.
Using a trusted offline OSM-based navigation app is way better
OSMAnd~ is great too. FOSS but only F-Droid builds the APK. It also crashed on GrapheneOS for whatever reason so I assume they have some real issues in the background with their code.
The free OSMAnd is shipped by them, so they build it, it might have less issues but it has less features.
Or you can buy OSMAnd+ from the playstore, which should also work on GrapheneOS.
Organicmaps is very smooth, releases their APK fully free (so you dont need to rely on F-Droid), but it is very minimal and lacks a ton of things.
OrganicMaps is easy, beautiful and intuitive. OSMAnd~ has like 30 times the features, which is a huge point for me.
Btw, there also is the underdog "mapy.cz", made by a Czech company. It is not FOSS but fully EU based. They push login and cloud stuff a lot, it has way too little offline features. But it is a good Googlemaps alternative as far as I tried it.