What will you do when DoT+ECH (encrypted client hello/encrypted SNI) is the default? block 17.0.0.0/8?
Honestly, not sure. At some point i think i will have to run a firewall when these guys won't allow custom dns anymore.
I had in past looked into putting a pfsense but its definitely not a good fit for raspberry hardware, if you have a fiber/gigabit internet.