I would mainly be pushing a good quality grass hay right now, timothy is most common, though it depends on your location. Drink bottle, maybe a bowl for water as well unless you're sure Nibbler knows how to use the drink bottle. Get some good quality rabbit pellets, grass hay based pellets rather than alfalfa pellets are best, make sure the fiber content is nice and high (around 20%). If Nibbler wasn't eating pellets before, or was eating a different brand, you will want to introduce the pellets slowly. Any sudden diet changes or food introductions for rabbits can easily cause stomach upsets and lead to gastric stasis. So start small, like a teaspoon of pellets, or even if introducing greens like fresh herbs or romain lettuce, a teaspoon sized piece of leaf to begin with until you know how they're going to handle it. If 24 hours later you haven't noticed any bad side effects (soft squishy poo, lack of poo or eating hay, sitting in uncomfortable positions, gas) then you can slightly increase the amount given until you're feeding the regular amount. For a rabbit of about 5 pounds in weight, the recommended daily amount of pellets is 1/4 - 1/2 cup per day.
All fruits and most vegetables like carrot etc, are considered treat only, and the most given should be about 1 tsp of treats a day. Leafy greens (herbs and lettuce etc) can be a larger part of the diet.
In regards to bedding, technically you don't need it, many rabbits will push it aside, but you can use it. I would recommend not using it and simply putting a litter tray in the cage with litter and toilet train Nibbler. If you want to give him something soft to lie on elsewhere, you can use a fleece blanket
You'll also need toys, toilet paper/paper towel tubes, old copies of the white pages with the covers ripped off, cardboard boxes, plastic baby keys, plastic balls etc. I would also either recommend either adding a hidey box inside the cage, or if there's not room, draping a towel over one end of it so that Nibbler has a secure place to hide if he/she feels threatened