I don’t think anyplace sells just the chip that strips off the addresses for each drop.
They also sell curtains that do not have the chip at the top of each drop. I have 2 w/out the chips (20x20 and 20x27) as well as icicle lights w/out the chip. In that case I think they are using a hard coded first pixel for each drop, though I am not 100% sure as I am not going to cut them up to find out. I did cut 1 LED off the icicles before for testing to see how it would get addressed if I relocated it.
These do not have the chips at the top: https://www.amazon.com/dp/B0CKX883BW Keep an eye on them I got them for $25 when Amazon Prime days were going on. (not sure if they are all hard coded addresses as I did not cut them up) If you want to read a long thread w/some crazy testing of the icicle lights it’s here: WS2812B....ish? Fairy Icicle lights
If you are ok with using the seed pixels vs strips, like were in the link. In that topic there is a link to aliexpress where you can buy a roll of 4 wire seed pixels that have the data return wire. All you have to do is solder the data out at the bottom of your drop to the return wire and you will have your data back at the top to be connected to the next drop. Those circuit board strips and rj11 connections are just an optional convenience.