The Glyphs panel does not contain greek statistics symbols. How is it possible to get these symbols into Indesign?
You pick a font that has them.
If you're on a Mac, you can use the Show Emoji & Symbols utility. In System Preferences > Keyboard > Input Sources, check Show Input Menu in the Menu Bar. From the "flag" icon, choose Show Emoji & Symbols (formerly Show Character Viewer). This article explains how to find a particular glyph:
The article lists a Windows utility which does the same thing.
Thank you Steve and Jane