I'm working on a custom keyboard, kind of like Gboard, but I didn't want to have to completely re-create the default iOS keyboard. Is there a way that I can just modify the existing keyboard? Or is there a package somewhere that has one available? I've exhausted all my resources I know of and caved and reached out to SO :). Let me know. Thanks!
You cannot. There are a few basic open source custom keyboards on GitHub that you might be able to repurpose, depending on their licensing and your needs.