Thank you masterxeon1001, proxe, and team!
[Q] [CTRL+Mark] for Vertex Group Bevels.
[Q] [B] [SHIFT+P] to cycle custom profiles.
Warning: Use only AUTO and VECTOR points. FREE and ALIGN points (= split and continuous Bezier handles) are not exposed in the Blender API and not saved to JSON.
CTRL drag profile points for 0.5 units of grid movement.
SHIFT for precise movement.
X to delete a point.
G to move points (X, Y)