For running applications: in addition to Flatpak (which is “cross platform” in that it works on most/all distros) there’s also Appimage. Appimage is the most like downloading a Windows application (technically it’s even more Mac-like) because you download a self contained program that just works. Not every application has a Flatpak or Appimage option, though.
Using json for IPC but a binary format for log files sounds insane to me, but alright.