Suing someone in the Philippines probably won’t be worth the effort for an $18 product. And the FBI probably will not care much about a $18 international fraud.
You presumably have their shipping address, so you can look up their local police department and report it as general fraud. Eg. The Toronto police have an online reporting tool for fraud and scams: https://www.tps.ca/services/online-reporting/
If it happens to be a slow day, or the person is already on their shit list (eg. on probation) maybe something will come of it. Having the gloating emails definitely helps. Or maybe the report just goes into a file until this person does this for a more expensive item and then it gets pulled to prove a pattern of behavior.
A lawsuit will cost you at least thousands of dollars if you can even serve the person. The FBI doesn't care about even thousands of dollars of fraud; they are busy chasing million dollar crime rings. Try reporting to your local police and see what they say - they will advise you it is not even worth your time to write out a report because it won't be investigated. Heck, my mom was defrauded out of $10k by a persistent group of people running a fake crypto investing company, and when she reported to the government body specifically responsible for investigating those cases, the nice man said, "Thanks for letting us know." They don't have time to investigate and prosecute minor fraud.