On board, while quarantined, they provide room service, including food from your designated MDR for the evening and breakfast from the MDR. They don't charge for sodas/water like they normally do with room service. They also reimburse you for the large internet package. I think they help you arrange a rental car if you are going to drive home. We already had one just in case, so they didn't need to help us. On debarkation day, you put your luggage out that morning after most guests have left their cabins. You stay in your cabin until someone comes to get you, after everyone else has left the ship. You don't go through the terminal but directly outside, where you collect your luggage. Someone from customs looks at your identification there. If you are picking up a rental car, usually at MCO, there is a bus with other quarantining cabins that takes you there. If you are going to quarantine in a hotel in Orlando, there is a different bus with other quarantining cabins that takes you to the hotels.
DCL pays for the hotel and food. If you are driving home, DCL reimburses you for any rental car, hotel, gas, or food costs incurred on your way home. They also currently give you a prorated refund on your cruise.