ISP Programmer with Serial and 5v/3.3v power
How about, connecting a tiny battery across the 3.3v output of the Pololu.  Lets assume a 3.7v LiPo, charged to 3.3v.
When the battery is connected at 3.3v, no current will flow.
When my device to be programmed is connected it will draw a spike of current, which will start to take the Pololu below 3.3v, but then the LiPo will start supplying current and stop the Pololu voltage getting dragged down and browning out.
The LiPo will then be slightly below 3.3v, so will get a Constant Voltage charge back to 3.3v.
Two potential issues I can see:

When the Pololu is disconnected from the USB will it be being 'back powered' by the LiPo?

When in CV charge mode, the only current limiting will be internal resistance of the Pololu output / LiPo cell, probably not an issue in practice due to the voltage drop being very small.


I know it is a hack, but thoughts welcomed.
Cheers
Kev