Embed a Google Maps / OSM Map on a website that allows importing KMLs and drawing polygons for submission as KML

I have found multiple examples of how to embed Google Maps or OSM maps on a website. However, I am looking for a (preferably free) possibility for the viewer to import their own KML as well as the feature to draw a polygon on the map which will then be submitted to me (the site owner) as a KML file, similar to this:

I am creating the site with WIX.

Please help! Thank you

Du meinst etwas ähnliches wie

nur das es KML Dateien erzeugt?

Maybe something similar to https://geojson.io ?