I don't see how pi-hole get affected by DNS via https, unless you are leaving out the part about computers, tablets, and phones using hard-coded DNS servers that use DNS via https. This is a trend, but a very small one right now.
DNSSEC does not do encryption: DNSSEC is about data origin authentication. Encrypted DNS is DoT or DoH, DNS-over-TLS or DNS-over-HTTPS (and maybe in the future DoQ, DNS-over-QUIC)