Install/Run Android Skype on ARM LInux?
One way to install Linux apps on Ubuntu is through Anbox. It's very resource efficient, using your Ubuntu kernel to run Android apps without emulating the Android kernel or running Android in a VM. However, it's still in alpha, so getting it set up takes a while and apps might crash or not work at all.

Also, you'll need to find the APK somewhere (e.g. APKMirror), as the Play store isn't included.