You can manually set Pi-hole as DNS server on each individual device.
This way, your devices will use Pi-hole directly and they will show up in the web interface with their own IPs.
The only way to have a "failsafe" like this is to have another Pi-hole device (with another IP), installed in another device and then adding both Pi-hole as DNS servers on the router.
If one fails, the other one will still be working.