@Mjm1963
The system should automatically populate with all the apps Sky has for it during the initial software update after the camera is plugged in. There aren't any optional downloads or any kind of app store, and Glass doesn't have an open operating system for app developers: it only hosts external apps such as Zoom where Sky has a commercial relationship with the app owner.
Which app(s) were you hoping for?
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Sky Glass 55" (on ethernet) & two Stream Pucks (one ethernet / one WiFi)
BT Halo 3+ Ultrafast FTTP (500Mbs), BT Smart Hub 2
