It turns out the people who want to be addressed by neutral gender usually don't care as much about Siezen and honorifics, so the systems I built usually just g

It turns out the people who want to be addressed by neutral gender usually don't care as much about Siezen and honorifics, so the systems I built usually just go with "Hallo" or "Moin". I even had one system which would go with "Sehr geehrte/r" for people who had chosen a title or set their language preference to "Deutsch (Sie)" and with "Moin" for everyone else.