I'm not sure I've grokked metamodernism enough, but based on what I have, it seems the protagonist arc is more or less coming to terms with the fact we are on an absurd interactive ride, and we can enjoy it and that's enough.
My understanding is that postmodernism is taking what was built by modernism and tearing it down, showing how it doesn't work, and otherwise deconstructing it and examining it piece by piece to the point that it loses all meaning. It is disillusionment with the modern world, and admitting that it's all bullshit. In a word: nihilism. Then, Metamodernism is taking those pieces and using them to construct things, just not the things you started with, and not using the pieces in the same way. And thereby adding meaning back into the thing, just not the same meaning as before. So you are still admitting that the original was bullshit, but instead of blowing everything up and leaving, you're constructing something that works for you, with full knowledge it is arbitrary. In a word: existentialism.
I don't think I've heard the term metamodernism before.... but I think no matter our circumstances we can choose to enjoy the ride. someone smarter than me said “Pain is inevitable. Suffering is optional.” I'm not always a good practitioner... (I worry, fret, over-think, stress, depress, etc) but it's front of mind.