Check the schematics, under the CAD Resources tab. If you understand the circuit, and the connections or solder bridges it might be come more apparent which pins and connections will be contented for use. The list is going to be pretty short.
The number of break-points the hardware facilitates is fixed. Modifying flash on-the-fly has it's own issues.
You can use as many BKPT# as you want. Variable levels of telemetry can tell you a lot about flow dynamics and interactions, in real-time systems this is frequently more desirable than dead-stopping a system, or introducing 100's milliseconds of non-responsiveness.
I'd like to see Segger offer an OB firmware for the the V3, V3SE implementations, and be willing to pay reasonable money for it.
