I can only save a KMZ file to my hard drive now. That is very inconvenient when I’m switching different devices. Why doesn’t Google create such a simple feature?
If you created KMZ file from your Google Earth map, you are able to use it in https://www.google.com/maps/d/ where you can deploy it and use it further on the web. And same applies for KMZ files created in My Maps then downloaded and used in Google Earth.
How to import KML/KMZ data to Google My Maps: https://youtu.be/IOaSY6R5RW0?t=13