I am player of Niantic games for more than 6 years, as far as I can tell - they are logging your interactions at certain points of interest, but not every location.
You can actually send GDPR request to them, and you will get your history back - many have done so, and there are only interactions that you intentionally do.
There are things like egg/portkey hatching, where your location is sent to Niantic in order to calculate distance you have walked, however i hardly doubt they are storing it, as they have enough problems with other mechanics due to server capacity.
Not to mention things like GPS drift, and GPS spoofing - the raw location and movement data is mostly useless.
I do turn my spare phone into hotspot mode while at home in order to get more distance - i get about 10km/hour just because my GPS is inaccurate. Imagine how useful this is, if all hardcore players are doing that.