Android Question Use ancient Greek characters


I am creating an app where I need ancient Greek characters.
I' m writing this:

Dim a as String = "τῶν Ἀποστόλων"
MsgBoxAsync(String, "")

But what comes out on the phone is this:
τ ν Α'ποστόλων

You see, in this example, second character (ῶ) of the first word is missing and first character (Ἀ) of the second word is not displayed correctly (Α').
I think this is an issue with the installed fonts of the phone (maybe ancient Greek is not supported by default).
Could there be a solution to this problem? I'd be very grateful if you could help me! :)
Thank you in advance