This is my prefered personal way of installing (proprietary) software packages missing in Clear Linux but available for other RPM based distributions.
It configures dnf to install all software into /dnf root in order to keep /usr clean, as intended by the CL paradigm. Most software, however, still wont be functional as they tend to assume to be installed into /usr, and therefore need manual fixing.
I suggest running dnf install --repo clear filesystem bash to create a minimal directory structure, besides adding /dnf/bin to the PATH, and adding /dnf/lib & /dnf/lib64 to /etc/ld.so.conf.
Use the build-fake-deps.sh script to build a rpm package with the missing requirements in order to avoid reinstalling dependencies already provided by the base CL installation.