UNOFFICIAL language for all apps. Platform https://translations.telegram.org/creece/ (for Android - Android-X - PC Windows - iPhone - macOS, except NekoX)
just click on it, and automatically changes to Greek language in any application
For MANUAL installation lng pack for NekoX, (also Android AndroidX) download file (https://t.me/tips_Greek_Telegram/225strings.xml) > just 3dots upper right on message > Apply localization file.
For Desktop windows, download file, Settings > keep Shift+Alt before select Language > choose file downloaded