PiHole can be configured to use DoH, as can OpnSense and presumably other local DNS and router servers.
PiHole can be configured to use DoH, as can OpnSense and presumably other local DNS and router servers.
I’m not sure you could even run pihole on 512MB RAM.
You can do it. I set mine up ages ago. https://docs.pi-hole.net/guides/dns/cloudflared/