it’s indicated that he does design a LOT of the equipment

Yeah I think that was the crux of my disillusionment with the character as a young adult lol: just the constant handwavy “rest of the fucking owl” implication that Bruce has been designing something somewhere between the pages, or well before the story began, when I come to learn that thing is a difficult problem in an active research space, or has been built already but required years and hundreds of engineers and scientists to implement, and the writers apparently didn’t check because Bruce’s technical ability was just a magic hat for the plot

the World’s Greatest Detective

Totally with you. That was something I was happy to see them revive in the Arkhamverse. And they really nailed that aspect of the character in that franchise.