Hi! 
Could a lightweight version of paraview be built with a QML interface and compiled to webAssembly to run entirely in a browser? Has anyone attempted this, and what would be the main technical challenges?
A QML front-end is definitely possible - see this blog post for an example.
Compiling it all to WebAssembly is theoretically possible, but there are likely some incompatibilities in ParaView-specific rendering classes when going from OpenGL 3.2 to WebGL that would need to be addressed. WebGL has a reduced feature set compared to OpenGL. VTK is in much better shape in that regard, which is good news.
I am enjoying all the recent vtk wasm webinars and examples kitware posted online. Good to know what to expect when it comes to Paraview. Thanks Cory for the insight and sharing the example