and most of them are flagged as off topic, because they are not completely related to programming.
The ones you have listed are not closed as off topic. They are closed as not constructive and duplicated as they should.
Off topic marked question can indeed be suitable for other websites but if they are valid enough are usually moved to those websites. Sometimes though they are not suitable for the entire SE network yet and should stay closed.
I want to ask about the other Stackexchange sites where these questions can be asked?
There are tons of SE websites nowadays, but probably the most close to SO is Programmers.SE. Take a look at their about page and see if your questions are suitable for that website.
Notice that not constructive questions on SO are usually not suitable for the entire SE network due to their being subjective. Programmers in the other hand is known for being a little bit softer at accepting questions, but this is not the case.