I tested both su and su - with poweroff, however seems like i did not do the same test with su - for shutdown since I assumed it wasn't there after the first fail.

In my original reply I was typing out every listing from /sbin # ls but then found shutdown was in there all along.

Thank you for your patience and for pointing me to the right direction.

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I am sorry to hear that you have the issue of constantly pointing people to certain parts of the docs.
I currently, kid you not, have the same exact issue at work.
I tell myself that if it isn't working then I need to look for another solution, but that's the hard part.

Hopefully I can try to tell you what made me a dumb user here and perhaps it will find a solution:

First: I would never think to look at the release notes to learn how to shutdown

Let me go read them now:

Google search devuan release notes gives me https://www.devuan.org/os/releases
I don't think I am in the release notes yet.
Click install because it is the closest to the Home screen I think I would find
Oh there it is, on the "home screen"

Woah!
Problem one: Users don't read

Release notes are 7.5 screens long - Lots of useful information in there though

Link 17 Broken
Link 18 is the gold

Yeah I see what you mean now, thats going to be a hard piece of tidbit to bubble up to the users who are just trying the distro for the first time, or who aren't aware of recent changes in Debian (aka me)

Before investigating this I would have said, a page on the website explaining the su difference would help, especially if it could grab search results like how to shutdown from cmdline for devuan, but it feels like this change is a bit outside the scope of the distro's website goals.

That's tough, I'm not seeing a solution for the sigh.
Sorry. I tried.

Not sure what the sigh is about, the su worked for me equally as su -

Unfortunately however

root@devuan:~# loginctl poweroff
bash: loginctl: command not found