Thank you for your inputs!
What I could do in the meantime is to get a source plane in vtk with as many points as my matrix, get the points as a numpy array and then do operations on them.
Are there any examples on how to manipulate point data and shove it back in the vtkPolyData object then?
It seems that the LIC works on point data and not cell data, so maybe it has more sense to build the matrices with points, do the operations and then create the surface with like a Delaunay2D?
EDIT: Programmable Source: Vorticity and gradient from numpy data - ParaView Support - ParaView
Something like that could maybe work, I can’t run the code yet, but seems like a good start