Save this link that describes a "bunny Heimlich" maneuver: https://coloradohrs.org/bunny-heimlich-maneuver/. Here's what it says:
Bunny Heimlich Maneuver
Rabbits often choke on pellets, especially if they tend to “gobble” their food. If you have a “gobbler,” you may want to spread his pellets out on the floor so he can’t eat as fast as he can from a dish.
It’s also very important to be sure that pellet dust isn’t included with the pellets. If rabbits sneeze, and then inhale, the dust can enter their nostrils, which generates mucous, causing them to choke.
If your rabbit is “coughing,” and trying to rid himself of the blockage, leave him alone. But if he isn’t coughing, and if his lips are turning blue, he needs your help. And you need to know how to perform the “Bunny Heimlich Maneuver.”
Place the rabbit on your forearm (right arm for right-handed people; left arm for left-handed folks) with his legs straddling it. Grip his head on both sides with that hand, and use your other hand to hold him tightly against your arm.
Lift him so he is just above the level of your head, and then quickly swing him downward. Obviously, if you don’t have a tight hold on him, you can throw him onto the floor, so be very sure that you have a tight grasp. It might help to wrap a dish towel around him and your arm, so that the towel helps hold him on your arm.
It may take several repetitions of this effort to dislodge whatever is choking him. Once he begins breathing, he may cough and sputter, clearing out whatever has been left behind, but his lips should begin to grow pink again. Don’t continue the Heimlich maneuver if he’s doing this.
It’s a good idea to visit a rabbit-savvy vet after an episode of this kind, since it’s possible that some of the material got sucked into his lungs, and to be sure that dental problems haven’t contributed to the episode.