Qt has a very powerful GUI editor that also works quite well. Using QML and Python it's not hard to create a cross platform app. Distributing may be a pain though.

Then there's Gambas on Linux (though tbat requires WSL2 or Cygwin to work on Windows). Gambas does almost everything VB6 does using an obviously copued GUI and language.

In general tools written for a single platform are better than their cross platform alternatives.