There are lots of switchers that will run from 0.7 Volts but with a 9 V output it’s harder to find!
If it is possible to settle for 5.5 or 6.5 Volts the MAX 1674/76, 1700/1701, 1703, 1705/1706, 1708, 1760/1760H, 1763, 1947, and a few more would do the job.
Even though some of these have a...