Using systemd-run --uid

I am trying to run commands from a root shell as other users. I am trying to remove sudo from it:

systemd-run --user --pty --same-dir --wait --service-type=exec sudo -u ubuntu make

I tried:

systemd-run --pty --same-dir --wait --service-type=exec --uid=1000 make

(removed --user as it only works on system context, added --uid= despite it being equivalent to unit's User= it only works on uid, and removed sudo -u ubuntu from the cmd) > Failed to start transient service unit: Transport endpoint is not connected Only mentions I've found of this cryptic error are about machinectl container/vms/remotes not being started. But in my case i'm using the systemd system of the very host. What is the correct way to use --uid parameter on systemd-run?