How should I track a mobile app landing page with firebase / google analytics

Right now I have a mobile app with both ios and android version using firebase. Users and events tracking is done with firebase. The firebase account is also linked to google analytics for better reports and analytics.

I can add inside both firebase and analytics a web tracking source which would be a third tracking source for this case.

But since I want to track a landing page and not a web version of my mobile app I feel that doesn't correspond to my use case.

What I would want is to be able to tell how many of my users downloaded the app by clicking on the landing page download button. I also would also like to be able to track how users got on the landing page. For example I would like to have stats on how many views and app download a post on a specific blog or a specific ad generated.

I though this would be quite simple to setup with firebase / google analytics but I'm not so sure anymore. If I add my landing page as a third web tracking source, I actually think it will affect the stats of my mobile app usage.

Does someone here had the need for something similar ? How did you set your landing page tracking ?