There's a similar — though very localised — thing in English with "themself."

The singular form is used, but it's far less common than the plural form "themselves." I often hear "themselves" used to refer to one non-binary person and it always sounds weird.

I guess we have to work with what we have. Is there an alternative in Arabic, like neopronouns?

This is based — I'm not skilled enough to help out with security advice, but if you need someone to sense-check a how-to guide or something let me know.