I would imagine as long as the “any old pc” meets the minimum system requirements, I don’t see why not. As you can download both to install on your system of choice.
Some hardware-specific addons might not work though.
I have not tested the most recent versions of it, but it’s only kinda comparable to TrueNAS. While you do get a web UI for managing ZFS functions where it’s lacking the more polished control that you get with TrueNAS, especially for things like replication.
I have run Houston UI on both Rocky and Ubuntu, as well as plain Cockpit and Webmin on Ubuntu and I use TrueNAS scale as my daily driver for my main NAS. Houston UI is far superior to plain old cockpit or even webmin. Houston is just no where near as polished as TrueNAS.