The problem is that sideloading is so difficult on iOS (you need a Mac, XCode, and then, after spending that $1k you realize that to keep the app on your phone for more than a couple days-one week, you have to pay Apple $99 per year) that people who would usually help open-source projects (where you use whatever tools you want and a free toolchain), have a much higher opportunity cost to getting involved with a iOS project.

If Apple had a mythical developer mode/SEP disengage button (like Macs and Chromebooks do) that voided the warranty, disabled the secure enclave (therefore Apple Pay and system-wide encryption), and put a big warning on the lockscreen in exchange for sideloading access to make development easier/cheaper, I think more people would do it.

Or if they let you build and compile apps on the iPad Pro that is super powerful but still can't be used for anything more taxing than word processing, but I've ranted about that on hn too much.