See MessagEase for a similar keyboard (not programmer-focused) with less keys but letting you use the swiping motion to type ordinary — great for fat-fingered people.
MessagEase has been my go-to for years. I swapped this year to thumb-key when MessagEase went to a subscription.
I love the ability to quickly copy, paste, select-all, type special characters, etc., all without having to do anything complicated. It took me a little bit of time to get used to the layout, but now I type exactly what I want, as I want it, without any auto-correct or automation needed. I make few errors and love the whole way of doing it. QWERTY makes very little sense on such a small screen, but it's what people know.
I'd call MessagEase-style keyboards good for programming too - no (need for) autocorrect, and the extra room lets you squeeze in most symbols and modifiers.
I switched to dvorak a few years ago and to thumb-key this year. I would say that thumb-key is much easier to learn than dvorak. I simply switched to it and about three months later, I realized I had gotten up to almost my original typing speed without any directed effort. I originally typed at 45 wpm on AnySoftKeyboard, and now I type at 40 wpm on thumb-key. This is in contrast to dvorak, which took six months of at least 15mins a day of dedicated practice time to surpass my original speed.
Did you continue to use Qwerty for work? I was in the fortunate position of switching to Colemak at a fairly non-critical time of life, so I cold turkeyed it.
Took about two weeks of daily driving until it was no longer painful, then three months until I had matched Qwerty speed. So probably similar to your thumb-key experience.
Faster than Dvorak. Unlike switching from fluent QWERTY to an initially slow other-layout, you're switching from the frustrating autocorrupt to something deterministic and predictable.
I picked it up to a usable speed within two days, helped by the fact that I use a lot of technical terms that autocorrect used to dismantle, so the baseline was much worse.
Oh that looks cool! I was really hoping it would have better emoji support than MessagEase as that is the one think I miss (the ability to search for emoji by name) but alas no.
Thumb-key also has many alternate layouts, including clones of MessageEase layouts. However, MessageEase layouts are easier to edit: directly on device, instead of via pull-request.
I've learned MessageEase, and it's great for that feeling of having a direct connection to what you're typing (no mistakes, and no annoying autocorrect messing you up), but I always found it slower than swipe-typing
Generally I feel keyboards on iOS are almost non-existent, especially combined with App Store's (lack of) discoverability. A simple search for keyboard brings up only GBoard and Microsoft's. And emoji and Unicode "fancy characters" keyboards. The only new keyboard I found today, thanks to this thread is called "AEI Keyboard".
I actually want to get around making something customisable. A keyboard that you will put whatever keys you want, wherever you want. iPhone is too small for a comfortable keyboard, otherwise.