Thanks. I now see the instructions for isolated mode. I'll stick them here for my reference. But, for others, I'd recommend going directly to the official download page and get them there.
Code:
You can also do an "isolated" install that only touches files inside the installation folder and does not need to be run as root, like this:
wget -nv -O- https://download.calibre-ebook.com/linux-installer.sh | sh /dev/stdin install_dir=~/calibre-bin isolated=y
I'll continue searching the internet and see if I can find anything specific about Calibre and Bazzite.