Yes that's where they list the compatible apps.
I don't think subs are purchased through their store, it's purely a place to download the apps onto an SD card for installation - subs have to be purchased either through the applicable mobile app or through the vendors web site.
For instance, I can install the Predict Wind app on my Axiom chart plotter but when it's opened I'm prompted for my username/email and password in order to work.
So I would assume that you would make Ventusky available to Premium subscribers only (?) as that also would give valuable data such as sea/tides/currents which would be great 👍
In their chart plotter user manual it gives the following information regarding the apps which you're probably interested in:
"Axiom-Series and Axiom 2-Series displays are based on different versions of the Android operating system, and this affects the compatibility of specific Android apk apps with each LightHouse 4 display variant.
Axiom-Series displays are based on an Android 6.0 (API 23) ARM7a (32-bit) system.
Axiom 2-Series displays are based on an Android 11.0 (API 30) ARM64 (64-bit) system."
Hope this helps.