Unfortunately, the service provider (in this case yours is Hulu) can only determine your local stations by your IP address, which is usually assigned based on your ISP's connection to the Internet itself. I don't know if Hulu offers any method of assigning your location manually, but that would be a question only they can answer. Your only other option is if Starlink can assign you to a closer ground station than you're currently using.
Calling Roku for assistance will not be of any help, as this is not something under their control.