Help Restrict App installation

[Thika]

Hey guys,
Need your help and advice on this, please...

Android 5.1, I have got some Chinese devices PlayStore disabled (These devices are used by our security with PTT)
I found out that some guys are transferring APKs by data cable and installing Apps.

Is it possible to restrict installation of Apps from OS side, so that even if they transfer the file, installation would be restricted?

Thanks a mil for your support

Tc.
Thika..