Does anyone know the answer to this question at this link:
Much needed thanks
Bsurfaces addon can create mesh from curves directly; why would you need to convert curves to GP strokes?
Bsurfaces operate on Bezier type curves so you’d need to convert Polylines (edit mode, T-pane, Spline Type) before. If curves are separated make sure you join them: selection order is important to get proper, not tangled mesh. Check if curve normals point one direction.
Edit: just in case… drop a plane into the scene, select curve object, Shift select plane, tab edit mode and press Add Surface button.