Linux

I suppose it's more difficult if your desktop environment doesn't support Wayland, so you'd have to replace it entirely. I can imagine that's a pain, but that's not exactly the typical use case.

Luckily, I doubt X.org will be abandoned any time soon, so the minority stuck in their old X.org exclusive environments will be able to use their programs unchanged for years to come. Eventually X.org users will be in the same position Wayland users were in years ago (having to apply workarounds for missing APIs to keep everything running smoothly) but I doubt that'll happen soon.

Clipboards work out of the box in the Wayland compositors I've used (Gnome, KDE, Deck UI), as does screen locking. Most automation also works, at least between X11 applications running under XWayland, but that's the "workflow" thing I mentioned; xdotool needs to be replaced by ydotool and maybe some DBus calls, depending on your setup, but a few aliases and an afternoon of work should work around those problems when the time to switch eventually comes.