I saw the new plugin PSU-Shelly in a message as I have Shelly plugs I thought I try it out. I tried to load the PSU-Shelly plug in, but ran into problems.
It is not listed as in the Plugin Manger in my Octoprint. I did hit refresh. I am not sure why this is as others have used it per Octoprint Plugin Repo web page.
I then loaded it with the URL method. While it did load PSUControl did not find it and it did not show up on the left side of the OctoPrint Settings Page.
I then loaded PSU Control - Tasmota using the Plugin Manger and it showed up on the left side and also PSU Control recognized it. Unfortunately, I do not have a Tasmota plug.