Hi,
Here my env. :
- Reterminal DM
cat /etc/os-release
PRETTY_NAME=“Debian GNU/Linux 12 (bookworm)”
NAME=“Debian GNU/Linux”
VERSION_ID=“12”
VERSION=“12 (bookworm)”
VERSION_CODENAME=bookworm
ID=debian
Here some check commands : 
journalctl -b | grep watchdog
Feb 16 17:17:00 rasp kernel: bcm2835-wdt bcm2835-wdt: Broadcom BCM2835 watchdog timer
Feb 16 18:30:02 rasp kernel: rtc-pcf8563w 3-0051: pcf8563_watchdog_init: watchdog1 is attached
axelone@rasp:~ $ ls -lh /dev | grep watch
crw------- 1 root root 10, 130 Feb 16 17:21 watchdog
crw------- 1 root root 248, 0 Feb 16 17:21 watchdog0
crw------- 1 root root 248, 1 Feb 16 18:30 watchdog1
My : sudo nano /etc/watchdog.conf
Is like as described in wiki
When i block the device, it doesn’t reboot 
sudo su
echo 1 > /proc/sys/kernel/sysrq
echo "c" > /proc/sysrq-trigger
Any ideas ?
Thanks a lot
Regards.