That doesn't make it legal or safe. Re-distributing copyrighted material is questionable even in Portugal.
But more importantly there's no guarantee the app binary was not modified and repackaged to include malicious code.
https://android-developers.googleblog.com/2018/06/google-pla...
They specifically cite being able to do this peer to peer.
Legality of distributing "free as in beer" stuff that isn't "free as in speech" is always an interesting topic, in the case of Europe, I suspect we'll see more revision on that front as these cases regarding the Play Store and the license changes develop. It's possible, for instance, that the EU might feel that preventing sideloading of a Google app "ties" it to the Play Store in a way they find distasteful.
It's interesting to me that as of yet, Google has tolerated APKMirror, likely because it's run by Google/Android enthusiasts, and not intended for circumventing Google's business model. I'd be very curious how Google distinguishes Aptoide as something to be stopped, but APKMirror as something to be permitted.