I have a Z5 Compact as well. Nice little phone, and quite fast. However, I don't think that many developers test their apps on a sub-5" screen, because I've encountered issues with several apps where controls overlap. For example, in VLC's file list the context menu button overlaps with the invisible scroll bar track. It is easy to scroll accidentally. Amazon Music has exactly the same problem, too.
The Android ecosystem is difficult to recommend, and a small Android phone is even more difficult to recommend.
The Android ecosystem is difficult to recommend, and a small Android phone is even more difficult to recommend.