If I search for Lone Echo 2 in the Windows-based Oculus app store I see results that show Lone Echo II: Trailer Experience as well as the first game, Lone Echo.
If I do the same search from within the in-headset Oculus app the results do not show the Lone Echo II trailer experience at all. Why the discrepency?
There are three different Oculus stores: Rift, Go and Quest.
Some games appear on more than one. Some don't. Rift is X86 & Windows based. Go and Quest are ARM & Android based. They are not compatible, games need to be rebuilt for each platform (which can require significant effort).
Lone Echo 2 is a PC only game, so it will appear in the Rift store. If you are using a Quest headset then it's store won't show it since the game isn't compatible with a native Quest.
However a Quest using Link or Airlink will emulate a Rift and let you play PC only games, assuming you have a good gaming PC to power it.
The desktop app only shows Rift games. The in-headset store only shows games for that particular headset. The mobile app and web store show games for all three platforms, you pick which platform you want to view from a menu.