If my piece of content is so unique and valuable around hiking backpack recommendations, that other reputable outdoor websites are willing to link to it and build the page’s authority, then I’d have a very real opportunity to rank high in organic search for these search terms (meaning, my page will come up first when someone searches for hiking backpacks).
To do that, you have to harbor a few fundamental guiding principles in your mind. Today, if you're at all serious about generating a full-time income (and more) from your online activities, then you need to focus on passive income as opposed to active income. Sure, the active income will help you survive. That's the scarcity mentality at play. But it's the passive income ideas that will help you thrive.
If you have a good idea for an app, and the skills to create it, then producing your own premium app can be profitable. However, with so many free apps available, it may be hard to convince people to pay. If you want to go down the premium app route, consider having a basic free version to encourage people to download the app in the first place. You can then provide the option of upgrading to a premium plan once users realize how useful the app is.