I went through a very similar experience on using keybr to learn Colemak last year. It was in anticipation of typing on a custom split ergo to improve efficiency.

I was really surprised by how easy it is to build up muscle memory, along with some decent speed/accuracy. However, I had to make a decision to unlearn most of my efforts and go back to QWERTY, as it was causing too much confusion switching between the two layouts. Colemak was also causing cramps between the shoulders and the neck on traditional staggered keyboards. Regardless, I am glad that I undertook this exercise, and occasionally do some tests for basic retention.