Unfortunately, Fivetran does not support Transformations (dbt or others) for Hybrid Deployment destinations.

I believe it would be a great feature to add to the current model for Hybrid Deployment.
Most of the time, companies that enable Hybrid Deployment use it for security purposes.
For the same security purposes, DBT Cloud or other DBT deployment options are more complicated to validate to the security teams.

Thus, Fivetran could help data teams accelerate their data transformation capabilities while keeping their cloud environment secured.