OliveTin does not need to run as root. It does not request any special permissions from the operating system that require root (as long as you run on ports above 1024, and it can read/write it’s configuration). So, you can run as any non-root user if you wish.
However, it is very convenient to run as root, as many users will need to run actions and jobs that do require root permissions.
There are no ways in OliveTin to specify which user runs an action, because the Linux OS has several great ways to do this already, and adding support for it in OliveTin just adds bloat when there are perfectly good ways that already exist.
actions: - title: Run echo as a different user shell: sudo -u bob echo "I am Bob."
If you are worried about security, you could run OliveTin as a non-privileged user, and use sudo rules to control what it can and cannot do.