Well, there's this thread and the point it makes:
I have been through every account of failed SN attempts. Vomiting has never been reported as a cause of SN failure. There are only two accounts that could conceivably have been due to vomiting: @Silasruin on 4/25/20, took 75% of 60g SN in 150 ml water, reported rapid onset vomiting and also...
sanctioned-suicide.net
And this case that involved both vomiting and (apparent) death:
Dear everyone, This thread will be about the documentation of the cbt of user @Moonicide (29 years old) Who took her life on Jan 12th at 00:30 EST. She was a dear friend of mine that I met on this forum. She loved this forum and it's users. The forum helped her allot during her last days. And...
sanctioned-suicide.net
So I wouldn't be *too* worried.
I personally have olanzapine which has antiemetic properties for the same reasons that metoclopramide does for example, just without the faster emptying of the stomach.
But I'm still taking into account the however unlikely possibility that I'll just wake up with a splitting headache or something, so no burnt bridges.