What are you studying? Could it not be argued to be part of your studies if you are doing a computer science course of some description?
Not unless you were getting paid for it, no.
well the border agents are not programmers and they would see it as WORK without pay.
work without pay is deportable under immigration laws
Assuming the OP is just talking about voluntary github commits and stuff like that, no they wouldn't. There are standards that have to be met for something being defined as work, like requirements to show up at a particular time and being managed by someone etc. If you're doing stuff that could just as easily be done from elsewhere and which comes with no obligation, that's not work.