As mentioned on the Discord, I'm proposing to submit Colemak-DH layouts to xkeyboard-config.
Norman, Workman, and Carpalx layouts are already there, so it seems reasonable that Colemak-DH should be included too!
Proposal is to have basic Colemak-DH, no extras or variants (such as Extend, or Caps to Backspace, or DHk).
This is what I have done for starters, still a work-in-progress (and not yet tested):
The implementation is similar to the existing vanilla Colemak one, which uses the US mapping as a base, then other international layouts inherit from that, making changes where necessary. Dvorak seems to do a similar approach too.
So, I have implemented the US (ANSI) variant, this uses the the angle(z) mod, and also acts a base from which other international variants can build. Interestingly, I note the US mapping does include the <LSGT> key (mapped to hyphen by default), so I have mapped that to Z in the US layout (in addition to <AB05>), so that non-US layouts that extend from it will automatically have the correct ISO Z.
In the existing files, only GB and PL layouts seem to have local Colemak variants that extend from us(colemak), so I have only implemented those for Colemak-DH using analogous configuration to the existing Colemak ones. I'm trying to make it as consistent with the existing approach as possible, and I also don't want to get into messing around with the Colemak implementation that's already there.
Feedback or extra patches welcome!