terraform providers have a nice property that they can be replaced with a custom compiled binary. Am I right that Pulumi pulls TF providers as a dependency and to achieve same result (== quick local bugfix), I'd need to recompile Pulumi provider ?

Yes - you can replace the plugin with a locally compiled binary just by dropping a file on your path with the name

pulumi-resource-cloudflare

where

cloudflare

is the name of the resource kind you want to handle (the first part of the URN used to register resources - typically embedded in the language SDK you are using, but you could manually call

pulumi.runtime.registerResource

as well if you want).