I have a fire tv and run adguard, which does the same thing as pihole, and I can barely tell it's on. It may block some tracking, but I get an increasing amount of ads in the fire tv GUI, not to speak of YouTube ads.

Sometimes I wonder if the people recommending pihole actually tried it. You get much better value out of ublock, smarttube, and so on.

This is a great suggestion. I've run two on my local network for about five years:

pi#1) My personal DNS resolver, which I manually configure on each device.

pi#2) The much less restrictive DNS resolver which my DHCP server automatically issues to all other network clients, including all phones and IoT [0]

Individual hosts can then manually configure their DNS to resolve to the local network router (or third-party DNS), which effectively bypasses both PiHoles (for that device, only).

[0] There is a method to use a firewall to capture all outbound DNS and force routing through PiHole (ifsense? I don't know), which may be necessary for hard-coded DNS-IPs. I do not know how to do this but it's not necessary on my network.

Often devices will have the DNS server hard-coded and never connect to the pihole DNS server. This is not just to avoid ad-blocking but to make the DNS more reliable and avoiding having lots of potential support issues around faulty DNS.

I've never used pihole, but on any decent router you can intercept outgoing udp to port 53, and redirect it to a destination of your choosing. DNS-over-HTTP ruined that however.