What exactly is a femboy zako? Like a certain outfit or style?
I think it's just a guy that acts or dresses feminine.
There are a couple of people on twitter who dress up and roleplay as male zako (generaly spandex and zentai suits.
Most are japanese (a xouple of whom say that they dont want to interact with foreigners in their profile), but there are a couple of english speakers there too.
Some of the english speaking zako roleplayers love to take requests and exchange photos (i did this a couple of times with one roleplayer on twitter (MaleZako) back when i was on twitter (i had to delete my twitter when i got into a new relationship and had to hide this side of me lol)).
The one i spoke to was very chill and loved taking requests, as long as his face was never seen