If you have your vet’s cell nr, I really think you should call her, if she says go to the ER vet, you go. If she says just monitor your bun, you do that. I only know that rabbits have died from eating avocado, but I don’t know how much is lethal and I can’t make any reassuring assumptions.
You can give a bunny activated charcoal at a dose of 1-3 gm/kg body weight. It would have to be mixed wioth water and syringed. We are not vets here and I’ve never given activated charcioal to a rabbit, but there are many mentions of it on various websites and we’ve had a case here on the forums where a bunny had activated charcoal, although administered by a vet.
Here is a web-site on animal posoning: http://www.vspn.org/Library/misc/VSPN_M01158.htm scroll to the section about activated charcoal. Rabbits can’t vomit and you should never try to induce vomiting in a rabbit.
Here’s the forum thread about tyhe bunny that got activated charcoal:
https://binkybunny.com/FORUM/tabid/54/aft/115545/Default.aspx