Reproduce native map chart legend colour scale

[prayner]

I am trying to recreate the following native map colour scale legend, which is populated using a master item with a custom colour scale:

The reason I am trying to reproduce it is because we want to isolate the colour scale (with filter functionality) without having the white legend background and surrounding text.

The only native chart type I found that could inherit the colour scale was the Radial chart:

But I cannot filter using this colour scale like I can with the native map object. Is there an alternative way to reproduce this object? Chart legends are not objects so I cannot isolate the legend that way either.