It’s a more robust solution than you’re looking for, but you can accomplish this using Home Assistant. Using the mobile phone integrations, you can share your location.

phonetrack nextcloud app for backend/website in combination with OsmAnd on your phone works great.

That isn’t the main goal of dawarich but family location sharing is a recently added feature

Have you had a look at the Location Tracker & Sharer category on F-Droid?

I haven’t personally used any of them, but seems to have recently updated apps in there that might be what you’re after

A privacy preserving location sharing system that shows you a map can only work with offline maps. If the maps arent offline, then that means the server delivering the map data knows where you are.

I dont know of an offline maps based live location app. There are plenty of non google apps that do this in a non private way as a primary or secondary function. Matrix/Element can do it and there are apps on fdroid (ToLoShare for example), that do it. But all of those have to somehow depend on a server that delivers the map “tiles” (chunks of map data near you) to show you a map. So they are all technically capable of tracking you.

The only really private way to do this is to share the coordinates through a secure channel in an automated way and then whenever you need it you open those coordinates in you offline maps app (CoMaps for example)

Zood location