You should do none of those things and enjoy your summer.
Pre-studying for M1 is pointless in general, and pre-studying for Step 1 is even more useless at this time. Especially considering it will be p/f once you take it, so your time will be better spent doing research, making connections, extracurriculars, etc.
If you must focus your attention on something besides video games (which is what I was doing after I quit my jobs before med school), then I’d recommend working out, cooking, and developing a healthy lifestyle in general. I wish I had time to do this right now but it is very difficult as an M2, and it will be for you as well. Good luck!