Work (Datacenter): RHEL, some SLES
Desktop: Kubuntu (just works, more or less - start with minimal install to avoid snaps)
Steam Deck: runs arch btw
For CLI, diff has already been mentioned; for a GUI application I'd recommend meld:
https://meldmerge.org/
Work (Datacenter): RHEL, some SLES
Desktop: Kubuntu (just works, more or less - start with minimal install to avoid snaps)
Steam Deck: runs arch btw