Based on the provided information, the most likely matchwinner of the Euro 2024 final between Portugal and France who is now on the board of the Portuguese federation is Cristiano Ronaldo.
Cristiano Ronaldo fulfills all the given criteria:
- He was a key player in Portugal's victory in the Euro 2024 final against France.
- He is widely regarded as one of the greatest football players of all time.
- He is currently a member of the board of the Portuguese Football Federation.
Other possible answers:
- Éder: He scored the winning goal in the Euro 2016 final against France, but he is not currently on the board of the Portuguese federation.
- Rui Patrício: He was the goalkeeper for Portugal in the Euro 2024 final, but he is not currently on the board of the Portuguese federation.
- Fernando Santos: He was the manager of Portugal in the Euro 2024 final, but he is not currently on the board of the Portuguese federation.
However, Cristiano Ronaldo is the most likely answer given his prominent role in Portugal's victory and his current position on the board of the Portuguese federation.
Please note that this is just an educated guess based on the limited information provided. Without more context, it is impossible to say for sure who the matchwinner was.