there is a dedicated volume button that you can press, then you can press it + fn, and + shift
but it should be mapped in the system, so if you are using the stock OS – try to switch to Rex’s image, you can find them in the forum, i recommend the trixie one
by dragging scrollbar.
you need to upgrade stock keyboard firmware, than you can do vertical scroll by using fn + ball, instructions are in clockworkpi github
no glitching spacebar, better working gamepad, better working ball, hor/vert scrolls by select + ball
read the qmk thread, it was answered more than once
About other os - yes I am thinking about switch to this os you recommended - now I think I have seen somewhere in this forum about luks /home - i want to do as well
And of course I will read about this custom keyboard firmware