Need advice on a power supply for my first build (pi 3b+)

So Im currently trying my hands with one of these builds as I figured it would be a fun experience and if all goes well maybe using my deck as a sort of anti distraction writing and school device as I struggle keeping my attention on work and am taking a no options approach. All i want to be able to do is run pi os and all that jazz so I'm currently running a pi 3b+. I have most of my parts figured but I still need a power supply of some kind as well as a screen (though I think I've settled on a HAMTYSAN upgraded version 7" non touch display).

But anyways so my question is due to my lack of knowledge in the subject, am I able to just use a generic power bank to keep the pi running. If so what would ya'll recommend for about 3-4 hours of life per charge. If not what should I look for instead? Thank you and I appreciate having a space to ask this as I don't really have anyone to ask on the subject.