Dutch is a very gendered language, we don't have many neutral options. So this video inspired me to go digging for a genderneutral option for "meneer" (mister) and "mevrouw" (misses, miss).
I used the website etymologiebank.nl to look up the etymology for the words "meneer" and "mevrouw", hoping to find a third option like in the video, but alas. It is as straightforward as it seems. "Meneer" comes from "mijn heer" (my lord, distinguished man), and "mevrouw" comes simply from "mijn vrouw" (my woman, distinguished woman). There is no third gramatical gender in Dutch.
So I looked up "neutraal" (neutral), it comes from the latin neutrālis, so it would give us the option of "metralis", however, compared to our other two it is a syllable too many. "Mealis" would be an option, but is also a name/nickname connected to names like Melissa.
But this did bring me to the word "neutrum" (neuter, gramatically neuter) an old word which has since been replaced with "onzijdig". "Metrum" would be a cool option, and close to the one used in the video. However, it is also a term in poetry (link in Dutch, metre in English).
This page also said that "generlei" was a gramatically genderneutral term meaning "onzijdig", and I must say, I love this one. "Generlei" has the suffix -lei, which comes from -leie, meaning "soort" (kind or sort). Gener- comes from "geen" (none). So "generlei" in this context means "of neither sort". The fun part is that the suffix -lei is used in many other words, like "allerlei" (of all kinds/sorts).
Which brought me to the title "merlei". It still fits the structure of "meneer" and "mevrouw" and doesn't seem out of place. And the best part, next to "generlei" (neither sort), we also used to have "enigerlei" (van een of andere soort. Of one or a different kind/sort), "velerlei" (van vele soorten. Of many kinds/sorts), tweeërlei, drieeërlei, etc (van twee, drie soorten etc. Of two, three kinds, etc.)
Which makes "merlei" way more inclusive, because bigender people can use "merlei" as meaning "tweeërlei", agender people as meaning "generlei", genderfluid people (such as myself) as meaning "velerlei", etc.
So, TL;DR: Some Dutch genderneutral options for titles, such as "meneer" and "mevrouw" are "metralis" (from neutral), "maelis" (from neutraal), "metrum" (from neutrum), and "merlei" (from generlei, gramaticaal onzijdig).
