I hope this is the correct category for this post. If not, please move as appropriate.
Remembering having read of a QWERTY - DVORAK hardware adapter a few years back I googled and found this:
But isn’t 150 USD too much for something that merely changes a handful of scancodes? Couldn’t it be done a lot cheaper especially with today’s Arduino etc availability?
Definitely. Or just changing the setting in the OS. I use macOS with Dvorak and don’t have any problems.
This company also makes key loggers. Not cool.
You can also convert your layout in the firmware, so the adapter becomes unnecessary with any programmable keyboard. With layers, you can even have QWERTY and a DVORAK layer, and switch on demand, no extra hardware or software necessary, and you can even deviate a little from the “stock” layout.
Here is a USB to USB converter that probably does what you need. It runs TMK as firmware. There’s also a (dated) review. If you don’t want to build your own, you can buy it for around 60 USD.
This is useful when you want to reprogram an old non-programmable keyboard, thus avoiding having to fiddle with the OS layout.
I stumbled upon the linked thread when I was looking for a way to have a programmable build-in laptop keyboard a while ago (unfortunately I never found an appropriate solution for that problem, as build-in keyboards are not connected via USB).
You might be able to use Karabiner Elements to do what you want.
I use it to map caps lock to F18. Beyond that, I don’t know much about it.
macOS only, AFAIK.
Hammerspoon might be useful as well. I haven’t used it, but it seems to be the more difficult to use cousin of Keyboard Maestro.