As far as I know the IAR C-SPY uses semihosting debug interface for transferring data to PC. So there is a chance you might be able to read the data over the semihosting debug interface also by other client. There is a little more info at https://pyocd.io/docs/semihosting.html

There are also other debug interfaces like SWO ro Segger's RTT which you could use for transferring the data.

Some tools also allows to read any part of RAM or ROM over JTAG, at least Segger's J-Link with its utility J-Mem allows it.