I was wrong. Indeed running Google Maps is not required. I have a feeling that Google device tracker is not reliable – sometimes I receive GEO positions with big delay and it had already happened that integration just stopped working (I had to re-export authentication cookies and it started to work fine).
Ive found it varies by device. My pixel will report me at home with pinpoint accuracy, whereas my sons Huawei puts him within a few houses.
When we’re travelling, he always shows a few miles back from me. My daughters iPhone is generally good but seems not to update often if she’s not moving much. That’s ok, but sometimes I’m not sure if she’s still or it’s stopped reporting.
This is why I use a combination of device trackers.