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

Android has its own Play Store, but with a bit of tinkering, you can also install apps from outside the official app store. Third-party app stores like Aptoide provide alternative options for app ...

Apple hasn't totally left old iPad owners behind. In addition to still signing the last iOS releases for those devices, you can still download software for them — assuming you know where to look.

Use the Galaxy Store Samsung phones and tablets come with the company's own app store preinstalled, allowing you to access apps outside of the Play Store without any weird workarounds.