Kanata has mouse emulation so you can drive a mouse using arrow keys: https://github.com/jtroo/kanata/blob/main/docs/config.adoc#m...
As a sidenote, I love my UHK. Just a joy to use, and it's so easy to customize. I don't have any experience with competitors like the ZSA Voyager, but the UHK's configuration software and macro language do make it quite pleasant to bend to your will. For instance, I do some funky stuff with macros and lighting here: https://www.cgl.sh/blog/posts/wnl.html
But, just wanted to share that I was similarly surprised to land on mouse keys as a preference. I tried most of the UHK modules which were also pretty good and have since tried various other trackballs and pads, but since trying UHK mouse keys, they're what I keep coming back to most, even since switching to new keyboards.
One issue I have with mouse keys is fear of using them in front of others though: every so often, if I need to click something particularly small and don't have a keyboard shortcut memorised (vscode panel resizing is one) it can sometimes take me a fair few embarrassing seconds drawing small squares around my target before I resort to actual mouse hardware.
For the amount of time and thought and effort people have put into alternative mice, I feel mouse keys are massively overlooked and probably have a lot of room for software/firmware innovation without hardware costs.
I felt most of the extra functionality and polish that I guess makes up the massive costs of UHK and ZSA wasn't actually necessary. It was cool and fun and useful to try a bunch of different stuff, but then over time, I wanted things to be simple and small which UHK and ZSA Moonlander aren't (ZSA voyager wasn't at the time).
All I'm saying is if you've got comfortable with a cheap Corne, I think you might feel underwhelmed if you spend a lot on something a lot fancier.
It was however stuck in customs for quite a while, but I guess that's what I get for ordering custom electronics from Israel right after those pagers blew up.
