Nytmare
David Jose
That's the hardest part of shared GMing is that all need to know the rules.
In some games shared GMing doesn't involve any kind of system mastery, and just has specific tasks usually left up to the GM that are passed off to one or more players.
In Band of Blades, you're playing the part of an entire regiment of soldiers retreating from a lost battle. At the beginning of the game, players pass the GM hat around and decide on which "Broken" they want to fight against, and which "Chosen" they march with, which dictates essentially which tropes and themes the game will and will not contain. Before each adventure starts, players adopt characters who are the officers of the retreating legion who, again, do some minor GM lifting. For example, the player playing the Commander chooses the specifics of the next mission and where the the adventure will take place, the Marshal directs which troops will make up the party, and the Spymaster gathers intelligence on enemy movement and activities.
In The Quiet Year, a map drawing RPG following the passage of a year for an orphaned community of some description, the entirety of the game's rules are read/learned/taught in the first 5 minutes of the game by players taking turns reading pages in a book. Each round, the role of GM passes around the table, as the player draws a card, chooses one of the two passages to read aloud and answer, and draws something on the map to mark the passage of time.