It's a bit silly to compare two dumpling styles as varied as pierogi and gyoza, even if we limit the discussion to Polish pierogi and traditional Japanese gyoza.
I should've been more precise. I don't want pierogi with gyoza stuffing, I want pierogi stuffed with actual gyoza (with whatever you put in your gyoza).
Ohh, so it's like carrying your udp packets inside tcp stream, so VPN (Virtual Pierogi Network) so that you can avoid SPF (Slavic Pierogi Filter). But keep in mind that it won't help you with DPI (Deep Pierogi Inspection) unless you scramble your gyoza inside pierogi layer. Still pretty handy when trying to import gyoza into slavic countries, but useless otherwise, because typical gyoza are not much smaller than pierogi, so you won't have any usable multiplexing, maybe max 2 gyoza per pierog and the shell is very similar anyway.
I guess gyoza encapsulation would work with some "farsz" padding to make a gyoza-stuffed pierog pass visual inspection. (I'm using my local Wagamama's gyoza for reference, your gyoza sizes may vary).
It's a bit silly to compare two dumpling styles as varied as pierogi and gyoza, even if we limit the discussion to Polish pierogi and traditional Japanese gyoza.