Draw a squiggle in Blender's Grease Pencil mode via the Python API

blender_squiggle.py

import bpy

# Create a new Grease Pencil object to hold the drawing
bpy.ops.object.gpencil_add(location=(0, 0, 0))
grease_pencil = bpy.context.object
grease_pencil.name = "ScriptedGreasePencil"

layer = grease_pencil.data.layers.new("Layer")
grease_pencil.data.layers.active = layer

frame = layer.frames.new(1)
stroke = frame.strokes.new()

# Set the thickness of the stroke (optional)
stroke.line_width = 100

# Define the points of the squiggle
points = [(0, 0), (1, 1), (2, -1), (3, 0)]

# Add points to the stroke
for x, y in points:
    stroke.points.add(1)
    stroke.points[-1].co = (x, y, 0)

# Update the view to see the changes
bpy.context.view_layer.update()