I am not sure but I think I saw somewhere you need to set your pi hole as the DHCP server in order successfully resolve your local DNS entries, can’t remember where.
protonmail has been seen sharing it’s users data with 3rth parties. I assume that extends to all their services if necessary.
the “default” blocks malware
quad9[.]net/service/service-addresses-and-features/
who cares? share good privacy preserving tips. don’t agree? do you and see if it works out.
tubular. you can then share from official youtube app to tubular and watch your recomendations with out ads and with sponsorblock if you choose. no way to auto sync the subscriptions tho