Their sigelei 100W/150W UI was nothing like ipv3 / yihi UI, even though it used yihi firmware, and did the same thing for all intents and purposes. I personally beleive they made the boards in house for those as well, at least they claimed as much, like they claim with this one. I tend to believe them, for at least the 150W I have taken apart, the physical board layout is a bit different from the SX330v3 that most people claim it uses, and I didn't see yihi printed on the PCB like I have with every yihi board I've used, even though it clearly uses yihi based firmware. Its possible they make the boards in house authorized from yihi, like the yosen SX300 boards which aren't made by yihi, but an authozied manufacturer. They could be straight up getting the boards from p4y and cloning them too. If you notice release dates from p4y and sigelei, sigelei has been a couple weeks/months behind the p4y offerings for products using the "same" boards.
However, its also entirely possible yihi makes boards with different hardware layout for sigelei.
All the speculation of who makes what could easily be cleared up from the companies, but most of these China outfits don't seem to like transparency.