Dear all, I tried to post same question to StackOverflow but they have closed my topic two times becouse they said "This question is opinion-based"...I do not understand but...ok
Now I kindly ask to someone of you an answer, please.
I'm developing an app that offers monetization through in-app purchases.
My initial intention was to distribute my app on the Play Store, but I've read about unpleasant restrictions, such as passing the app test, disclosing the developer's private information (name, address, etc...) to the Play Store, the possibility that the Play Store might close your profile at any moment, the inability to offer alternative payment methods, and finally the Play Store's revenue.
PREMISES
I plan to create a website for deploy and do SEO work, so deploy will take place "exclusively" outside the Play Store.
That said, my questions are:
1 - Can I use Google Cloud and Google App Engine to host my app, or I will be obliged to use alternative methods? (My app already uses Firebase Realtime for a database.)
2 - Can I use Google Play Billing? Will it work if I don't distribute on the Play Store? If not, what are alternative billing systems I can easily find as extensions in MIT App Inventor?
3 - What's the best way to share my app from a website? (links? where they should pointing, etc...)
That's understandable that you want to avoid some of the restrictions of the Google Play Store while still building a robust application. Here are the answers to your questions regarding using Google services and distribution methods for an app distributed "exclusively" outside the Play Store (sideloading).
Google Cloud and Google App Engine Usage
Yes, you can use Google Cloud and Google App Engine to host your app's backend services, regardless of how your Android app is distributed.
Google Cloud Platform (GCP) is a suite of cloud computing services that is separate from the Google Play Store's app distribution platform.
App Engine is one of the services within GCP and is designed for hosting web applications and mobile backends.
Your app's use of Firebase Realtime Database (a Google service which is part of the Firebase suite, built on Google Cloud infrastructure) already demonstrates that you can use Google services without being on the Play Store.
Google Cloud services are generally billed based on usage, and your project only requires a valid billing account, not a connection to the Play Console for distribution.
Google Play Billing
No, you generally cannot use Google Play Billing for in-app purchases if your app is distributed "exclusively" outside the Play Store (sideloaded), with a few narrow exceptions primarily for testing.
Requirement: Google Play's policy requires that all apps distributed on Google Play that offer in-app purchases of digital goods must use Google Play's billing system.
The reverse is often true: If you are not distributing on Google Play, you are not required to use Google Play Billing and, in fact, the system is designed to work primarily for apps installed via the Play Store. The integration is tied to the Play Store's infrastructure, which manages purchases, licenses, and subscriptions.
Testing Exception: Developers can sometimes bypass the distribution check for license testers to sideload debug builds, but this is strictly for testing, not production use or revenue generation.
Alternative Billing Systems
Since you are using MIT App Inventor, you will need to look for extensions that integrate with third-party Payment Service Providers (PSPs). Common alternatives for mobile app payment processing include:
Stripe: A very popular and developer-friendly payment platform that offers extensive APIs for one-time and recurring payments.
PayPal: Offers various payment solutions that can be integrated into a website or app.
Specific Extensions for App Inventor: Search the MIT App Inventor community forums and extension directories for billing/payment extensions, often integrating with one of the major PSPs.
Best Way to Share Your App from a Website
The best way to share your app for sideloading from your website is to provide a direct download link to the APK (Android Package Kit) file for your app.
Hosting: You would host the final, signed APK file on your website (which could be hosted via Google Cloud/App Engine, Cloud Storage, or any web hosting service).
User Action: When a user clicks this link on their Android device, the file will download. To install it, users must have the "Install unknown apps" or "Unknown sources" setting enabled for their browser or file manager (depending on their Android version). You should provide clear, simple instructions on your website about how to enable this setting for a successful installation.
Security: Always digitally sign your APK file and ensure you provide clear instructions and warnings about the security implications of sideloading from non-official sources, even if it's your own trusted website.
Thank you @Taifun for sharing results of your research.
But I need to receive the confirmation from an expert (as you) if the AI is right or is wrong.
I well know that I have the possibility to ask to AI, but only an expert can check if AI is right or not.
You could use AppHosting, on your firebase project, coupled with FirebaseStorage, to host a static website and provide links to your apps, but you could use any website host to do much the same.