Help a newbie to make a diy handheld console.

[Ggc_1987]

Hello to all forum users! I'm alredy a retropie user but i have make subscription on this forum only today.

In this year i have the desire of making a diy handheld game console from scratch in a snes controller (i want to make on as small i can for play games from nes, some snes, gb, gbc, some gba, pico-8, sega master system, sega mega drive and some from neogeo and mame) running on a raspberry pi zero with a little ili9341 lcd, maybe 2.2" or 2.4" if i can squeeze it in.

My first question is: i see the adafruit power boost, for 5v output from 3.7v battery, but it's very expensive. The ones i can found on aliexpress with prices around 50 cents are ok?
And for the battery, can i use iphone ones (a friend of mine have a smartphone repair shop and i can have one for a little price and they are very little and slim)?
I know it's difficult built, but i'm not in hurry.

P.s.: i alredy have other handheld consoles(PSP, DsLite, 2Ds and an old gameboy advace) and computer (Next Things Co. Pocket C.H.I.P., where i discover the awesome pico-8 virtual console) but i need a smaller one to play outdoor, specially for pico-8 because the pocket chip is way too big for be really portable.