On a side note I was once able to get a very precise location even with permissions turned off, simply by virtue of 2 devices being on the same Wi-Fi network, the other device having given permissions.

For one they both appear to the outside as the same IPv4 address, and Wi-Fi doesn't travel that far so you can usually presume they are at the same location. There are other ways like having one device hog bandwidth in a slowly modulated fashion, and have the other device pick up on that modulation in streamed data.

This isn't related to the parent comments and I highly doubt any major apps actually implement this but just pointing out that such a side channel attack is possible.