Hi @kevin.sallee!
One more thing I can think of is using a shader to draw the line (curve?)
Shadertoy holds many examples, here is one
In Defold, you can currently set only a few shader constants (4, with 4 floats each), but that should be enough for your purpose of sending a few coordinates. All that’s needed is a sprite that is rotated, and sized to span the area which contains the lines.
Here is one post which mentions this a little, and here is an example that demonstrates a very similar approach.