ShiftOut question for Hannio flipDot Display

I'm back on subject with some news and questions.
I've tested @allObjects's code. I've got strange behavior of the picoboard: pb to upload code, have to unplug+plug to handle the board.
with a simple loop to flip one pix at a time, i've got the same behavior than with my previous code. Some dot flips in random order...
I have retest some code with an arduino, and it work very accurately.
My question is about logic level (3.3v vs 5.5v) with shift register et encoders... is it possible that the strnage behavior is due to this shifting?
I've bought online this night a shift level breakoutboard.
I will retried with it at the end of the week.
so wait and see.

@allObjects: You use A0 pin for the latch (nssPin) do i need an Analog Pin? On the pico board, the size of this pin is smaller (difficult to clip or solder), therefor i use an other pin. is it a pb?
You've written

Init your 3 pins - data, sclk, rclk - as output and set rclk high and you are just fine from the get go.

Do i need to explicitly use pinMode(xx, 'output')? and an openDrain argument for the nssPin?
Thanks for your time.

regards