The weird thing about pdf417 is that there is a lot of helpful info our there, up until a point. It's like everyone is collaborative and asking/answering questions up until the point they really figure it out, but those last few steps never much make it into open code.
A couple times a year I go searching to see if anyone has implemented solid pdf417 in WASM yet. It seems like a natural fit to me, and I am sure people have done it, but I have yet to see anything publicly available.