vailable_countries entry, add it.
		if ( ! isset( $fields['available_countries'] ) &&
			class_exists( '\WC_Payments_Utils' ) &&
			$this->proxy->call_function( 'is_callable', '\WC_Payments_Utils::supported_countries' ) ) {

			$fields['available_countries'] = $this->proxy->call_static( '\WC_Payments_Utils', 'supported_countries' );
		}

		$fields['location'] = $location;

		return $fields;
	}

	/**
	 * Get the fallback URL for the embedded KYC flow.
	 *
	 * @return string The fallback URL for the embedded KYC flow.
	 */
	private function get_onboarding_kyc_fallback_url(): string {
		if ( $this->proxy->call_function( 'is_callable', '\WC_Payments_Account::get_connect_url' ) ) {
			return $this->proxy->call_static( '\WC_Payments_Account', 'get_connect_url', self::FROM_NOX_IN_CONTEXT );
		}

		// Fall back to the provider onboarding URL.
		return $this->provider->get_onboarding_url(
			$this->get_payment_gateway(),
			Utils::wc_payments_settings_url( self::ONBOARDING_PATH_BASE, array( 'from' => self::FROM_KYC ) )
		);
	}

	/**
	 * Get the WooPayments Overview page URL.
	 *
	 * @return string The WooPayments Overview page URL.
	 */
	private function get_overview_page_url(): string {
		if ( $this->proxy->call_function( 'is_callable', '\WC_Payments_Account::get_overview_page_url' ) ) {
			return add_query_arg(
				array(
					'from' => self::FROM_NOX_IN_CONTEXT,
				),
				$this->proxy->call_static( '\WC_Payments_Account', 'get_overview_page_url' )
			);
		}

		// Fall back to the known WooPayments Overview page URL.
		return add_query_arg(
			array(
				'page' => 'wc-admin',
				'path' => '/payments/overview',
				'from' => self::FROM_NOX_IN_CONTEXT,
			),
			admin_url( 'admin.php' )
		);
	}

	/**
	 * Check the onboarding source and ensure it is a valid value.
	 *
	 * @param string|null $source The source of the onboarding request.
	 *
	 * @return string The validated onboarding source.
	 */
	private function validate_onboarding_source( ?string $source ): string {
		if ( empty( $source ) ) {
			return self::SESSION_ENTRY_DEFAULT;
		}

		$valid_sources = array(
			self::SESSION_ENTRY_DEFAULT,
			self::SESSION_ENTRY_LYS,
		);

		return in_array( $source, $valid_sources, true ) ? $source : self::SESSION_ENTRY_DEFAULT;
	}
}