Is it allowed to wear headscarf for muslim men?

No. It is forbidden for men to look like a women and it is forbidden for women to look like a man, but in countries like Morocco some (gay) men wears headscarf. There are LGHBT+ versions of islam and some islam looking religions are allowing to wear a headscarf.

Depending on country and region it can be punished by law and/or by civillians.