Hi Viviane,
Thank you so much for visiting the Disney Parks Moms Panel with your question! How much fun to celebrate your son's birthday at Walt Disney World.
I think that you have chosen two excellent options for celebrating this special occasion. Both options are fun for the whole family! On a
Pirates & Pals Fireworks Voyage, your son will enjoy being a pirate with a swashbuckling crew, and weather permitting, a view of Wishes Nighttime Spectacular fireworks. At
Mickey's Backyard BBQ, he will partake in a fun backyard style picnic, with the added bonus of energetic entertainment, dancing, and characters. Because you mentioned that your son is very energetic, I suggest Mickey's Backyard BBQ. The pavilion in which Mickey's Backyard BBQ is held is open-air and large. There is lots of room for little ones to run around, plus dancing is built into the evening. While the Pirates & Pals Fireworks Voyage would certainly be entertaining and amazing, if your little one needs space to run, this is probably not as good a fit as you will be on a boat for quite a while.
Either way, do be sure to pick up a "Happy Birthday" button for your son while you are at Walt Disney World. These buttons are available free of charge. When he is wearing a birthday button, it will be truly magical to hear cast members and other guests alike wishing your son a happy birthday. Sometimes, a birthday button can inspire a little extra pixie dust on a vacation, like a complimentary birthday cupcake. This kind of pixie dust is not guaranteed, so do not expect it, and then it is even more magical if it does occur.
Have a great time planning your magical vacation, Viviane!