Thanks for the suggestion!
Right now the code to support that feature isn't implemented. The driver chip we are using does have this capability, but it will take a bit of time to implement and verify everything.
As a temporary measure, I just added additional buzz functions to give everyone 6 different lengths of buzzes (125 ms to 1.5 s). And will be looking into adding an additional function with variable duration in the near future. As noted, there will be some limits to protect the hardware, but need to double check on those before I say anything specific.
Thanks again for the suggestion, am excited to roll out that feature in the near future.