Mine threw up every time I brushed her teeth more than 15 seconds until about 2.
We let her “win” but settled for just the toothbrush in the mouth w toothpaste everyday. Our current dentist said getting toothpaste on the teeth was almost as important as getting food off, so sometimes we just put toothpaste on her back molars (the gaggiest spot) w our fingers.
She’s just turned three and we do the ABCs twice through so prob 30-45 secs. Our first dentist said if we weren’t getting 2 full minutes in twice a day we had to change what we did. I was not dealing with kid vomit everyday, no way.
Knock on wood no cavities, but the song she recognizes (and knowing it’s short etc) plus finding a toothpaste she likes (hello strawb w fluoride) helped. And skipping the back molars if she’s sniffly/gags, but luckily we outgrew that.