Comment by jjtech

This is sort of what Mach does with "out-of-line" messages: https://web.mit.edu/darwin/src/modules/xnu/osfmk/man/mach_ms... https://dmcyk.xyz/post/xnu_ipc_iii_ool_data/

(this is used under-the-hood on macOS: NSXPCConnection -> libxpc -> MIG -> mach messages)