I've actually got all the code to work now except the joystick part, which is the biggest (new) part for me for this keeb. I've been on the QMK discord (that's how I knew to update QMK to resolve QK_BOOT haha, although I'm not entirely sure the combo works...) What do you mean read the joystick input pins once per scan instead of in every if statement?
edit: yeah config_common is deprecated according to the QMK discord. very unfortunately I actually have no idea what I'm doing with QMK/C++ code (esp the joystick part) in general and have just been kinda sticking things I've found on the internet in in hopes of something working out but no luck so far