malingen_lockne You dont necessarily have to switch to using Googles location service.
Getting a first lock can take some time. Being outside can help a lot.
The phone has to download various datasets that help to resolve the location in the future. so having a network connection also helps speed things up. Without any network connection the phone will pick up the PSDS almanacs that are very slowly broadcasts directly from GNSS satellites, takes more than 5 minutes. If you have an internet connection it will quickly download these almanacs.
See a few paragraphs down in this section https://grapheneos.org/faq#default-connections
These almanacs eventually go stale so if you dont use location for some time and you are operating without a network connection you will have to wait for them to download from the satellites again.
If you have a SIM in the phone and a network connection the phone will use A-GNSS to speed up getting a lock on your location
There are details a few paragraphs down in this section https://grapheneos.org/faq#other-connections
Once youve got the various datasets downloaded the phone will be able to get location more quickly even without a network connection. However having a SIM active helps a lot.
If you live in a city and are in buildings a lot and still find you have trouble getting a location lock you may want to consider using Googles location service as Jdjdoefndbej suggests.