Why do you want Colemak on your phone? I switched to Colemak for my physical keyboard years ago, and didn't keep up my QWERTY skills, so I'm fairly crippled typing on a QWERTY keyboard; but I have trouble typing on my phone with my thumbs.
Presumably people like us are exactly why it's included on external keyboards for iPadOS.
I too use Colemak for physical keyboards and Qwerty for soft keyboards.
It is nice to have the consistency available. Though, I don't really have a need for it. Only case I can thing of is typing a few, key memorized passwords. I don't really remember the actual password, just the motions. Kind of a pain to motion it out and translate it to qwerty.
Presumably people like us are exactly why it's included on external keyboards for iPadOS.