I use Google Location Sharing to continuously share my location with a few friends. It's quite nice. Makes planning easier. Also, maybe it'll help with this stuff haha.
I shared problems in another comment here - TL;DR: worked seemingly good some 3+ years ago, started being flaky before covid, and seems much worse since covid.
So even if remote area was covered with cellular network, I would not rely on location sharing to show where I am not even where I was.
And although on one hand going from being at same place for hours if not days (home during covid), and then in just 10-15min reaching another place without any or with really bad cellular reception could be messing with optimizations of location sharing.
I recall few situations where both wife and I were next to each other, both phones running google maps at the moment, each hitting on refreshing/retrying getting the other ones location - and thing still showing us as currently offline.