Thank you for contacting Printerbase.
Unfortunately no Brother don't support Greek as a language option on the handheld printers. I have also checked the Dymo label printers and these don't either. The only other option is to get one of the Brother QL label machines that connects to your computer and design your label on the Brother P-Touch software.
Take a look at the Brother QL-810W - https://www.printerbase.co.uk/brother-ql-810w-thermal-label-printer.html
You can only get white, yellow or Red labels however you will be able to print in Greek.
Please do let me know if you require any further information.