If you want to do both road and gravel with the bike, and you care how fast you go on the road, one nice answer is two sets of wheels. Keep the existing gearing for gravel.
Then a second set of wheels setup with a faster road tire, and a 10-33 or 10-36 cassette
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You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.