After some trial and error i come up with using a ESP-01S, a I2C display, a MAX3232 mini converter board, a AMS1117 3.3v regulator, a passive buzzer and a T6845-C powerbank board and a 18650 3.7v lithium battery.
The T6845-C was perfect because it had the female USB Type-A to plug in the barcode reader and had the 5v step up built-in for the reader and the 3.3v regulator.
Project page and code:
For the "revised version" im going to fit all electronics inside the reader itself and only the screen will be on the outside. The 18650 batt fits perfectly on the handle.