From Fedora Project Wiki
If you're new to Fedora CoreOS feel free to do whatever you like. Maybe try to convert an existing system you own to Fedora CoreOS. Most of all: Please explore. Have fun. Try to break things!
If you're not new to Fedora CoreOS please try to test out some of your existing workloads or workflows on the next stream of Fedora CoreOS. Rebase existing systems, or start new systems from scratch with your existing Ignition configs. This type of testing is the most valuable in helping us keep the disruptions during the transition as minimal as possible.