Hello,
I agree that privacy is something that is VERY important, especially in our modern age. However Privacy from our ISP is nice, but Microsoft still has their own tracking in windows, As I (and others) have asked for in many places, PLEASE LET US DISABLE ALL MICROSOFT SPYWARE, AND CRAPWARE IN WINDOWS 10.
As for cpuprohky, good point, and alexatkinuk Pihole is a DNS server based adblocker, and this article is directly about DNS. as for Chromecast, people like ME, use Google Chromecasts with our windows PC's. As DNS is one of the backbones of the Internet, It does directly effect the use of devices like PiHole and Chromecasts, furthermore it effects anything that needs to resolve a name to IP. As your statement indicates a lack of knowledge on what DNS is, and how the internet works, I would advice studying the topic. If you would like, I can provide the names of some good resources.
Now to answer @cpuprojky's question:
as for PiHole, It already supports DNS over HTTPS, below is a link from PiHole explaining how to set it up.
https://docs.pi-hole.net/guides/dns-over-https/
Chromecast's should not be affected (depending on what your doing) As screen casting is a intranet matter, and video streaming the chromecast connects to it's own DNS servers, (your computer functions only as the remote, the device works 'mostly' on it's own).