I'd start by stepping back further:
- How do you create custom content in this third party application? Do you own the source code, or is it surfacing up a simple web app that you'd embed Qlik into?
- What web technologies are you familiar with/ prefer working with?
- Which platforms will the app run on? Some platforms block third party cookies by default in some contexts, which means you can't use our current iframe solution
- What do you want to embed - is it a whole sheet layout or are you willing to build a more embedded experience using one of our JS frameworks
- What method of authentication does this web app use? You'll likely want to ensure that users don't have to sign into the app, and then into Qlik Cloud - thinking about auth up front will provide a better experience for your users- what is the mobile app written in, what technologies are
Also, please note that for Qlik Cloud, you should refer to our Cloud developer portal rather than our client managed help site link provided by @Christopher_prem_ , as there are differences in capabilities between the two platforms. A good starting point (an overview of the available technologies) can be found at https://qlik.dev/tutorials/overview-of-embedding-qlik-content-into-web-apps
