I am not sure really.
We are using artifactory as an artifact manager.
I imagine that keeping a unique format simplifies deployment but I hardly know anything about this.
However I have found out how to do what I wanted, I tested on my personal fedora 31 distro on a toy example mini.package
# install R2spec
sudo -s dnf install R2spec
# build the package
R --vanilla CMD build ./the_source_dir
# create rpm out of the package tar.gz
R2rpm --sources ${HOME}/CodeProjects/R/mini.package_0.0.0.9000.tar.gz --keep-sources --debug --force-spec
# install the rpm
sudo rpm -iv /home/statquant/rpmbuild/RPMS/noarch/R-mini.package-0.0.0.9000-1.fc31.noarch.rpm
# remove rpm
sudo dnf remove R-mini.package-0.0.0.9000-1.fc31.noarch
Heavy lifting if performed by the great utility r2spec
And specs are described https://fedoraproject.org/wiki/Packaging:R#R2spec