If you're already thinking about trying it for a year or two, you're serious enough that a teacher will be far more helpful than an app, and a cheap, small, non-weighted midi keyboard will limit you a lot.
> But if you just want to make music in a modern way (on the computer)
Acoustic or digital, music is more than a series of button presses. All the things I mentioned apply even if the only thing you want to do is play 4-chord pop songs.