Although Apple was expected to bring sideloading on iOS 17 owing to pressure from the EU, the company skipped it without even a mention. However, we have a workaround to enable iOS sideloading ...

In general, you should install apps outside of your phone's app store only if you have a very good reason to.

How to install iMessage apps in iOS 10 and how to use iMessage apps to send stickers, share videos and play games inside Messages on iOS 10.