No, `swaymsg` is specific to sway, not wlroots. It won't work with any other compositor (wlroots-based or not) unless that compositor also binds $SWAYSOCK and serves the i3-ipc protocol.
That's probably true for protocol-level things but still doesn't cover as much as you'd think. For example, with X (possibly just Xorg but at least everyone standardized on that) I could run `setxkbmap` to set keyboard layout. Now as far as I can tell, wlroots does have a proper way to control keyboard layout... but it's up to each and every compositor to hook it up. So naturally, when I went to try a cool new compositor I found, I discovered that it doesn't actually support that. In fact, I couldn't find a way to configure keyboard layout at all in that compositor (don't recall which, but it was wlroots-based). So I threw up my hands and went back to X11, where one command controls the keyboard on literally every window manager I have ever tried.
