Wow such a great answer, thanks for sharing the thoughts that went into this. It's crazy that there are so many considerations when taking into account the limited speed of light.
What you describe can be done with self-hosted dawarich instance + the owntracks app. It records location history and lets you visualize it in a web interface.
Yes I've also tried it and reached similar conclusions. Do update it to the latest version though, as I did report an issue with non ASCII characters and for me it got fixed in v0.4.7+