You can export placemarks to a file and then use your own tools to sync. There's no reason why every single app has to include the kitchen sink.
If it regularly exported automatically, it could get picked up by a syncing app, but otherwise...
I already do this with as many apps as I can.
The average user is sticking with the default Apple or Google offerings, not looking for privacy respecting, FOSS, fully offline alternatives.
On my phone the on-device backup can be found in /storage/emulated/0/Android/media/com.whatsapp/WhatsApp/Databases, and I remember reinstalling WhatsApp, logging in with my phone number, and it found the backup and restored the messages.