Just like unclutter does for X, it would be useful to have a setting for the amount of seconds of mouse inactivity after which to hide the mouse cursor.
You can use this tool to hide your mouse under Wayland, I've just written it and I'm happily making use of it:
Just as a PSA for anyone stumbling here, Sway can do this natively also, f.ex seat * hide_cursor 8000
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Just as a PSA for anyone stumbling here, Sway can do this natively also, f.ex
seat * hide_cursor 8000