Everything I read says it's a feature enabled in what ever compositor you choose, if your compositor supports it. Why isn't there a general purpose keybinding program like setxkbmap? Does it just not exist yet or must it be built into the compositor?
I've read [this stackexchange thread] on something related but it all seems to be using XKB which should imply I'm using XWayland?
Xremap, despite the name, supports both X and Wayland, and can be used to move modifier keys around. Configuration is done with YAML but is otherwise pretty easy. I personally use it for full Emacs keybind emulation.
Personally, I’ve used interception-tools with the caps2esc plugin. Not the easiest to set up but it allows me to press caps lock for esc and hold it for ctrl. It bypasses the lack of a programs being able to read keystrokes of other programs by intercepting them closer to the hardware level. You can also do lots of other cool stuff with it, but I’ve yet to find anything else that lets caps lock work as both esc and ctrl.
If you are using kde, then this feature is right in the settings menu. I have caps lock bound to compose. I dunno about other DE's.