I used to be an organizer of Séminaire Mathjeunes during 2023-2025, which is a community (with a history of 17 years!) of math-loving youths living and studying in the region of île-de-France. As a tradition, there is an after-seminar-dinner, and it is free for speakers. So if you are going to visit Paris and you are willing to give a talk for a free dinner, feel free to contact the organizers! At any time, you are welcome to join the mailing list.
A github repository still under construction that might be interesting for some people.