Hi there,
So are you building it with the West debug switch, so it can load the ELF file the openOCD will connect to?, Check out these threads ,maybe they turn on a light 
🤠 nRF54L15 Xiao USB West Flash How to; - #2 by PJ_Glasso
this one has some GDB and OpenOCD.
read the how it works part, may jar something loose 
💥 The Xiao gets a Debugger... Seeedineers make MAGIC! - #11 by PJ_Glasso
HTH
GL 
PJ
So we are on the same page, You build it with debug image and flash it, then You connect to it- You HALT it- look at registers- Set Brake_points- Tell it to Go.
Rinse and repeat… 
I think it’s this portion…
arm-none-eabi-gdb firmware.elf
(gdb) target remote :3333
(gdb) load