Here's a bit of information on your question. Currently, many countries have already legalized online gambling, such as the UK, Malta, and Sweden. If you need more details, I recommend looking at the official websites of each country's regulatory bodies. As for recommendations, deal with the CPA (Cost Per Acquisition) system, it can be useful for those who want to monetize their traffic. Personally, I turned to revenuelab for information about
where gambling is illegal. Their blog site provides a good overview with up-to-date data. Good luck in researching the topic!