Hmm… the engine is available at https://github.com/elizagamedev/mkxp-oneshot - a workaround could be to build it yourself?
The actual Linux port was worked on on this repository. I used make-oneshot-linux.sh to build the Steam version of OneShot and a small modification to mkxp.pro's line 12 could make it build OneShot without Steam bindings, but the script does not install other dependencies so it will not work by itself. My old build instructions from here don't work anymore but should contain the list of dependencies that need to be installed in order for OneShot to successfully compile.