Doesn’t help if the device has a baked in DNS address and just ignores your settings tho. Amazon and Google devices seem prone to that. After blocking everything on the common DNS ports except the PiHole, some of my devices have been acting kinda sluggish.
I wanted to do that as well, but I can’t redirect outgoing traffic on my router, just block it entirely. Sadly it was the only device of that series not supporting OpenWRT (sigh)… Next one will either have to support that or be a DIY project… Have been starting to self host my stuff already and I’m not planning to stop there!