We used to use Matisse on our team to make mock ups and even generate the initial code for Swing user interfaces.
I'm investigating moving to Jetpack Compose and one of the hot questions is, where is the WYSIWYG editor for Compose? Something basic which will take care of component layouts and spacing for us, and export to code at the end.
Live editing of the view after the fact would be amazing, but is out of scope.
I had a bit of a play with Figma, but the usability was extremely poor compared to Matisse and can't seem to do much of anything without plugins.