Most of our systems today employ hybrid systems where servers are *nix based and coded in Node, Angular, SQL and non-SQL implementations, JavaScript, and Java.
Handhelds are typically in JavaScript with Angular or React elements and rely upon API calls to the servers. We normally distribute handheld applications in Google Play and the Apple Store, but for internal security needs, we also have simply distributed APKs for Android.
We have also coded and still support systems in C#, COBOL, Assembly, and C++.