Here's a suggestion I got from @Deleted User - He pointed out that in reality, nanomachines would probably cause a lot of problems in other species that they're not designed for. They'd likely trigger immune systems and cause clotting and other bad stuff. This would probably happen for humans too but in SARP it's long been established hemosynth plays nice with humans. IC it was probably designed that way because Nekovalkyrja were designed to work with humans. Anyway, I thought this was a great observation and it fits into the recent discussion about Yamatai/Nekovalkyrja being seen as overpowered. By adding it to the lore that standard HS only works on Nekos, Minkans, and humans, we can help clarify these limitations.