Does Raspberry Pi have a watchdog timer? I don’t see any mention of it in the BCM2835 technical documentation… but searching online, indeed I do see that there is a watchdog timer module available.
First, enable it.
sudo modprobe bcm2835_wdt
echo "bcm2835_wdt" | sudo tee -a /etc/modules
Now, you can use your favorite watchdog daemon software like
watchdogd to control it, or roll your own.
20200715/DuckDuckGo raspberry pi watchdog
20200715/https://www.domoticz.com/wiki/Setting_up_the_raspberry_pi_watchdog
20200715/https://blog.kmp.or.at/watchdog-for-raspberry-pi/
On Raspberry Pi 4, the watchdog timer kernel module is loaded by default, you just need to run some software to enable it and ping it to get it all set up.
20200715/https://raspberrypi.stackexchange.com/questions/108080/watchdog-on-the-rpi4
So, all that said, Raspberry Pi is “airworthy” to be used as a critical part of a home network, where stalls cannot be tolerated and a watchdog timer is a must.