Q. Can I side-load UWP apps on Windows 10 LTSB?
A. Yes. While Windows 10 LTSB (Long Term Servicing Branch which is aimed a specialized machines) does not include the Windows Store or in-box modern applications, it still contains the full UWP (Universal Windows Platform) stack which means if there is a UWP application that you wish to have on LTSB then it can be side-loaded using mechanisms such as DISM and PowerShell. The reason the Windows Store etc are not included is LTSB is designed to not update components with new functionality post-deployment which occurs with Windows Store applications automatically. For most desktop scenarios LTSB should not be used and instead Current Branch for Business.