Art by @eesiart on Twitter.

Note: This can get all Quests in the game (available in your current format), excluding Rogue ones, so if this were played in Wild it could have a chance of getting the original Un'goro Quests. As for how many cards Oso would shuffle, it would be dependent on the Quest's condition. For example, the original Taunt Warrior Quest from Un'goro would shuffle 7 Taunt minions into your deck, or the Discard Warlock Quest would shuffle in Discard cards. As for the new "Draw 20" Warlock Quest, you'd need to get more creative, but it would likely shuffle cards that draw, etc.

Is this likely to ever be added to the game for its pure complexity? Heck no. Is it an interesting thought experiment? Maybe. And why not give that interesting of an effect to a Vulpera.