Halal Charity Raffle Inquiry

As salamalikum warahmatullahi wabarakatu, I recently came across an online charity raffle that caught my attention, and I wanted to seek your guidance regarding its permissibility in Islam. The raffle allows participants to enter for free, but it encourages voluntary donations towards the designated charity. It's worth mentioning that there is no specific amount mentioned, so in theory, one could participate without contributing any money. The proceeds from the raffle are intended to benefit the charity. Given these circumstances, I have two questions that I would greatly appreciate your insight on: Is it considered halal (permissible) for a Muslim to participate in such a charity raffle where a voluntary donation is encouraged but not mandatory? Does the absence of a required donation make a difference in its permissibility? If someone were to win a prize in this charity raffle, would the winning prize be considered halal (permissible) for them to keep and utilize? Jazak Allah