I recently built a Pi 4. I'm considering stetting up Octoprint for my CR-10. However, If I understand it right, I'd need to wipe my current setup and use the Octopi OS image? Correct? Octoprint is not just an app that can be installed on an already set up Pi? In other words, to use Octopi, I have to lose everything I already set up on the Pi 4?
You can setup OctoPrint on any system that runs Python.
Here is a guide to set it up on Raspbian:
Thanks for the link. Next question, if I did install OctoPi, would all the other apps (LibreOffice, Blender, etc) run as they do on Raspbian? If so, then I'd need to figure out which OS was more work? My Pi is not just for my 3D printing.
OctoPi is Raspbian with OctoPrint and things like haproxy, mjpg streamer preinstalled. So the apps would work, however OctoPi comes without a desktop GUI and all the apps you mention, so you would have to install & set them up again. Depends which setup you think would be longer and more effort.
OctoPi is based on Raspbian Lite and it doesn't have a desktop (or LibreOffice, Blender, etc.) installed for a very good reason. When OctoPrint is actively printing, response time is critical to prevent artifacts from appearing in the print job. Everyone who wants to add a desktop and lots of desktop applications says "of course, I won't use those things when OctoPrint is actively printing" but when print job times are measured in hours or even days, it is hard to be that disciplined about it.
In the long run, I believe you will be better off with two RPi systems, one with all the bells and whistles and one running OctoPi without them connected to your printer.