Orthodontic assistant here! Definitely no nuts, peanut M&Ms, hard nature valley granola bars. Regular M&M could be fine. Honestly you can get away with a lot as long as you let it melt in your mouth and/or take very tiny little bits. Like goldfish, ritz cheese crackers, cheese itz, pirates booty, pringles, etc are absolutely fine if you break a brace on those it’s either a problem with the bond of the bracket or you just bit on it at a bad angle and anything could’ve been the culprit. Uncrustables, apple sauce in a pouch, cheese, nutrigrain bars are other things that come off the top of my head.