What?! That's crazy! I would have never guessed because it's such a well spread dish. I actually couldn't resist looking it up, and apparently there are some deer blood dumplings https://www.tasteatlas.com/blodpalt obviously, not something modern people would be making, I imagine!
Yeah, store bought wrappers are the way to go, I tried making my own one time and they didn't turn out good haha!

Hope you scout them out and make some, gyoza are absolutely delicious! Thank you!