Maybe/app/models/plaid_item/provided.rb

module PlaidItem::Provided
  extend ActiveSupport::Concern

  class_methods do
    def plaid_us_provider
      Providers.plaid_us
    end

    def plaid_eu_provider
      Providers.plaid_eu
    end

    def plaid_provider_for_region(region)
      region.to_sym == :eu ? plaid_eu_provider : plaid_us_provider
    end
  end

  private
    def eu?
      raise "eu? is not implemented for #{self.class.name}"
    end

    def plaid_provider
      eu? ? self.class.plaid_eu_provider : self.class.plaid_us_provider
    end
end