Thanks for sharing that perspective! I have not delved too far into k, though I have been a few times confused and discouraged by the fact that there are different versions of the language that are not compatible with each other, and some are proprietary (if I understand the state of the language correctly). Is there a specific version that is best to learn first?
ngn/k is a performant FOSS implementation of k6, but it has many constraints and limitations that may make composing large programs difficult. It may be the best dialect for tinkering and learning the language. https://codeberg.org/ngn/k
oK is a slow browser-based FOSS implementation of k6, with fun bells and whistles like "iKe", a visual livecoding environment. ngn/k and oK have diverged a bit, but are largely similar: https://github.com/JohnEarnest/ok
Q is a K-derived language built into kdb+; this is probably the most commercially viable dialect to learn, with the best educational materials (I recommend Nick Psaris' Q Tips), but it is proprietary, with (last I checked) free licenses available for personal use.
If you've seen Decker you may also have been exposed to Lil, which is similar in many ways to Q. It is more verbose and less expressive than Q or K, but I've generally heard people say they find it comparatively accessible: http://beyondloom.com/tools/trylil.html
Edit: I just realized that you are the creator of https://beyondloom.com/tools/specialk.html and https://beyondloom.com/decker/index.html. I just want to say that your work is awesome! I've really enjoyed reading through your website many a time.