This numeric format allows users to craft a custom QGIS expression
to format numbers. The expression can use the @value variable
to retrieve the value to be formatted, and then use any standard
QGIS expression function to format this as desired.

It can be used anywhere QgsNumericFormat is accepted, eg layout
scalebars, elevation plots, layout tables, and color ramp
legends

Sponsored by the Swiss QGIS User Group