Converting -3.7V to -32V (both negative), Is it a boost or a buck?
It would still be called a boost converter even though the output is lower absolute potential than the the input.  I would recommend developing both the +32V and the -32V from a positive +3.7V input.  You will have more luck finding devices that will do that.  Many of the datasheets for voltage converter ICs will have an example for generating negative voltages.

An alternative is that you could use a transformer coupled isolating converter to provide the -32V or both outputs, then it doesn't care where ground is. There are off the shelf devices from manufacturers such as PICO who may have something that meets your needs. Some of those have dual outputs.