Thanks for looking at this so quickly!
No idea about the equivalent mknod command. Using strace on Linux shows that both `mknod p` and `mkfifo` results in the exact same `mknodat` system call so `mkfifo` could probably be always used ?
It's still not working, I don't see any error regarding the mkfifo now, I attached the tramp debug buffer. I tried creating the fifo manually on the macos laptop and running the command
cd /Users/dam/ && exec 2>'/tmp/tramp.EIPAXu' env INSIDE_EMACS\=28.0.50\,tramp\:2.5.2-pre PS1\=/ssh\:laptop.lan\:/Users/dam/\ \#\$\ sh -c while\ sleep\ 1\;\ do\ echo\ \$\(hostname\)\ out\;\ echo\ \$\(hostname\)\ err\ \>\&2\;\ done
And there, it's working, I can cat the fifo and see the stderr output. No idea why tramp seems to stall. Running over tramp there is just no output in the stdout nor the stderr buffer.
tramp-debug.txt