I downloaded an apk from mobilism and before I install it, how do I go about ensuring it's not malware or an unsafe app? I'm all for buying apps but I hate all these subscriptions...
There are plenty of things that scans will not pick up that you still likely don't want your apps doing.
However an alternative app store I use is F-Droid. Which only hosts apps that are open source. This means that it is significantly less likely that anything bad will be on the apps. Since the source code is available for anyone to review.
It also means that everything on there is legally free anyway. 😀