Hi Tomasz, yes, in our regular release with default industrial config e.g., v1.6.1, we already enabled gdb in both service os, and guest os, but all based on Clear Linux. So from acrn hypervisor perspective, i think there should be no limitation, especially for UOS debug.
We did not try Zephyr gdb yet, but normally if Zephyr support/build gdb in image(suppose doable in zephyr native), it should works as guest. Anyway will double check with Zephyr for more debug experience, keep you updated then, thanks.