I didn't see any tutorials specific to the heatmap type, but my teammate, @Kabirdas & I worked on an example for you.
We took the GeoJSON download from the Mapbox docs and copy/pasted it in the GeoJSON section of the Mapbox component
Paste the GeoJSON data here:
Then check on this setting:
Then, copy + paste this code from the Mapbox docs to the style section (it needs to be an object in Retool, so we don't need the map.addLayer() part):
**and remove the source: 'trees' key value pair
This particular tutorial has a lot of data, so it's not the most performant in Retool, but hope this helps!