@MikeEitel Have you had a chance to try them with WLED yet (and if so do they work properly)?
There are many variants. Some work easily with WLED, some require setting up a custom layout (since there are 19 or 20 pixels skipped after each column), and only the first column works with WLED in others.
(Hence my above question about if Surplife ones work!)
Edit: src & to create a “custom layout” (not required for the curtain asked about @ the top of this thread) see Mapping - WLED Project
Describes a variant that works easily with WLED.
& the following comment is the most confirmation I’ve found as to how they are programmed:
I know from someone who has been to the factory that the process of programming the addresses of these LED involves shining light at the LED, using it as a photocell, to tell them which device is being programmed via commands over the wire. Don’t recall if they use a projector or a laser. I would expect the protocol is something along the lines of “If you can see light now, you are row x”, and similar for Y to program a large array quickly. It may be that higher than normal voltages are involved to do the write operation.