Hello,
Welcome to our forum and thanks for contacting us with your question!
You can read more about using latitude/longitude in Highmaps on our official docs, here:
https://www.highcharts.com/docs/maps/latlon. The example attached in the article is showing workflow with mappoint and bubble, but it should guide you to achieve similar results with coloraxis / heatmap.
Let me know if you have any further questions!
Kind regards.