Here's how you can move all your saved places from Google Maps to a more private and open source solution, Organic Maps.

First, get your data from Google Maps. Go to https://myaccount.google.com/yourdata/maps and click on Download your Maps Data.

Then use this handy converter: https://github.com/rudokemper/google-maps-places-to-organic-maps to get a KMZ file.

Open the KMZ file in Organic Maps and you will have imported all of places into a new list.