Comment by sidkshatriya

FWIW... I have modified packages on Fedora and installed them. The workflow is very simple... of course, not as simple as NixOS but here goes:

# clone the package definition

$ fedpkg clone -a <name of package>

$ cd <name of package>

# install build dependencies

$ sudo dnf builddep ./nameofpackage.spec

# Now add your patches or modifications

# now build the package locally

$ fedpkg local

# install locally modified package

$ sudo dnf install ./the-locally-built-package.rpm