Sculpt 'relax' verts to UV

It would be great to be able to relax verts with the Sculpt tool towards the relative UV spacing, so that a mesh with UVs could be projected onto a retopo ref and then brush relaxed to lessen texture distortion without modifying the UVs.

Are there any similar tools in other 3d apps?

Try this and see if that is what you asked for.

http://www.digitalfossils.com/Download/NVil-Sep-19-19.rar

  * A new basic streamline tool, Brush_RelaxUV. Relax vertices base on existing uv settings to reduce uv distortion.
  * When this basic streamline tool, Brush_Relax, is activated, it will do RelaxUV instead if Shift key is depressed.
  * Subobject mode > Geometry > Create > Sculpt > RelaxUV.

This option, Edit > Options > Preserve UVs Enabled, can also be useful for tweaking vertex position where the uv is good but vertex position is not.

Thanks Kun, you're the BEST!
This works especially well for relaxing triangulated areas.