# Mount the qcow2 as a RO filesystem
guestmount --format=qcow2 -a ./CentOS-Stream-GenericCloud-8-20200113.0.x86_64.qcow2 -i --ro ./centos-image
# Make a copy, which will take some time...
cp -a -R * ../centos-stream-8/
chmod -R u+w ./centos-stream-8/
# Unmount the `qcow2` image
# You can also remove this directory, but make sure the directory was unmounted properly
# we don't need the `qcow2` image anymore