What really allows it to work is that my /home dir is on a separate partition that I do not re-format with installs. Thus, all of my personal configuration is still saved, and I just have to install the application to read it.
I have been doing the same for a while now. I need to print out my dnf installed apps and keep them somewhere in /home. There are the odd packages that dont go through dnf (pip, npm, tarballs etc) but in general those can ge gotten as needed if it were ever to come to that.
My current fedora (34) started out as fc14 about 10 years ago and I’ve just upgraded every 6 to 12 months. I have HW RAID so as disk die (which they often do) they get replaced and the array just rebuilds itself.