Having your nails painted isn't nearly as scary as it sounds. You might get a second glance sometimes, but mostly people don't really care and it's all in your head. Mine are a nice flashy corral color right now and I haven't had any negative interactions. In a worst case you just kind of get the feeling that people are actively trying to not comment on it.
It honestly works great as a good social filter. Sometimes I'll run into a cashier or someone similar in passing who seems uncomfortable with it(usually older folks), but it's otherwise a good way to find other queer folks or allies in the wild and start a conversation.