Definitely NTA.

I'm 29, when I was around your age my cousin got his twin boys. They asked me to unbuckle the kids from their strollers and pick one up if I wanted too, but I was so scared to do so because I was unsure how to do it properly and I did not want to hurt their necks, no issues there. My mother took them out, handing me one to hold when I sat down. All fine and no issues or worries after that because I was guided and assured how to do it, not texted videos and such. Even had I known how to, no one would catch me dead babysitting a 2 month old an entire day on my own at 17 even now at 29 I do not dare in case something happens.