For each example in this post, I will be linking to the sea otter pools at the Vancouver aquarium. That location has the coordinates of 49.30063,-123.13149
To link to it, you would use ‘geo:49.30063,-123.13149’.
Depending on your web browser, pasting that into the search bar might prompt you to select which map website you want to use to view that location. For me in Firefox, it asked me to pick between Google Maps and OpenStreetMaps. It’s even more convenient on mobile, where it asks me which map app I want to open it with. Both CoMaps and Google Maps handled it correctly.
If you are writing a post or comment on Lemmy/Piefed/etc., you can place it in the second part of the markdown link format: [Sea Otter Pools](geo:49.30063,-123.13149). This would output like this: Sea Otter Pools
The linked OpenStreetMap wiki page has a good summary of how well various apps support this scheme. A lot of people here are active in the open source space, so please consider following up with the apps that are currently missing support or have partial support for this: https://wiki.openstreetmap.org/wiki/Geo_URI_scheme
EDIT: I forgot to mention, you can also use apps like this one to convert maps links between each other
https://github.com/jakubvalenta/GeoShare
https://f-droid.org/packages/page.ooooo.geoshare/
https://apt.izzysoft.de/fdroid/index/apk/page.ooooo.geoshare
I don’t see how which app on Lemmy would matter as far as geo-coordinates because all you’re linking there is literally a latitude and longitude of coordinates. And if they paste it into a web browser, it wouldn’t matter what lemmy client they use.
Frontend apps need to recognize the markdown as a valid url scheme and parse it accordingly
Voyager does not, for example
Some apps display/handle links in weird ways. It’s the same reason why the OSM link above lists information about support on different messaging apps. I assume some of it comes down to sanitizing inputs, or whether a specific library an app is using has support for it, or if an app offloads the task to the system share sheet
For example, the links work for me in Boost for Lemmy and Summit, but not in Voyager. Another user mentioned submitting an issue to the developer of their particular app