The root zone file is publicly distributed by IANA [1] so you can download it and ignore the servers themselves. Then your lookup (from the resolver you're running yourself) starts at a particular country's top level.
As for censorship, because it's hierarchical, they'd have to remove an entire country code from the root servers.
... or until the blocking starts at the root name servers. There are only a few of them.
The root zone file is publicly distributed by IANA [1] so you can download it and ignore the servers themselves. Then your lookup (from the resolver you're running yourself) starts at a particular country's top level.
As for censorship, because it's hierarchical, they'd have to remove an entire country code from the root servers.
[1] https://www.iana.org/domains/root/files