Table (desktop) apps are mostly written for Windows, there is Python and Java as rule does not apply, write in C# and "ubiquitous" C++.
The mobile app is mainly popular for Android, next iOS, Android Yes, Java, but there are a lot of specifics, not the fact that Java EE and iOS - Obj-C/Swift, in fact it is one language, and again, C++ on both.
Your question is very few specifics about what you like. we have to focus and "fit" for the real tasks that are in different firms.
What, what purpose?
What about the database? Imagine server, but its client is not notorious browser and your app on Android, iOS, Windows, on database server and your application access it provides, administration, viewing.
automation of typical activities of a simple user
For example what?
maybe even make a smart virus of some sort.To develop
the viruses it is "atypical" direction is for your business or freelancing is close to the business, I chose this path, but I try to avoid subjectivity and therefore do not hide the fact that he is controversial and you should think whether you are applying individualism to such an extent and ready for a long time to achieve this before they can tasty to eat.
What about analyzing
viruses? I would like to write the antivirus which detects the virus? Deeply embedded in the core of the system and protects itself from them, and the system too (firewall, file protection from deletion)? Now that's a traditional work team.