How to block/redirect traffic from outside the United States to my AWS Lightsail Wordpress instance

Hello.

If you use AWS services, you can set up AWS WAF to block access from outside the United States.
https://repost.aws/knowledge-center/waf-allow-block-country-geolocation

However, AWS WAF requires CloudFront or ALB, so using it with Lightsail requires some ingenuity.
Please note that AWS WAF incurs charges when used.
https://aws.amazon.com/jp/blogs/compute/integrating-aws-waf-with-your-amazon-lightsail-instance/

By the way, Lightsail's firewall seems to have a maximum of 60 rules, so it may be difficult to configure it to allow all US IP addresses.
https://repost.aws/knowledge-center/lightsail-considerations-for-use

13. Number of Lightsail firewall rules: You can add up to 60 firewall rules for a Lightsail instance. Each source IP address is considered a different rule. IPv6 rules are counted towards this quota of 60. The maximum number of source IP addresses that can be added in a rule using the Lightsail console is 30. To add more, you can use the AWS CLI.

Hi,

Yes, you'll likely need to use WAF to configure the rules. Here is a blogpost which may give some idea around how one can integrate WAF with a Lightsail instance: https://aws.amazon.com/blogs/compute/integrating-aws-waf-with-your-amazon-lightsail-instance.