Re: Privacy?
DoH (DNS over HTTPS) will neatly disregard your Pi-Hole, it's what DoH is designed for.
The clients that has DoH functionality will use an internal list of DNS-servers. You may or may not change this list depending on the whim of the developer (adware and malware will probably not allow you to edit or disable this list).
This means that you need to configure every DoH aware application you run individually, if you want to preserve your privacy/security/sanity.