I have a 2010 Mac pro, can I carbon copy a new drive and place it into my 2010 IMAC?
Yes, this will work fine, and I boot multiple Macs from the same boot drive all the time.
A warning though, if the OS on your Mac Pro was above the OS on your iMac, you could be missing some Firmware.
This might not be a big deal at all, and you may never even notice, but I ran into an issue where I couldn't install High Sierra on a new SSD I got for a dumpster-pulled Mid 2011 iMac with a failed GPU and HDD.
I was running HS on it that was cloned from another Mac and it ran fine, but when I went to do a fresh install, I couldn't install it because firmware was missing due to the previous failed HDD not having HS installed.
I had to replace the newly installed SSD with an OEM Apple HDD, install an OS prior to HS on that drive, then upgrade to HS installing the firmware.
After that, I swapped the temporary HDD for the SSD, and the High Sierra OS installed fine on it.
If your iMac already had High Sierra on it, the firmware was most likely up to date, so you don't need to worry about it.