Looking at the maths of this:
There are 350 people travelling to Gaza on 20 vessels or an average of 17 people per vessel. From Barcelona it will take them two to three weeks sailing/ motoring.
To feed and water 17 people every day for 2 to 3 weeks means that there is simply no room to transport aid to Gaza. They would be lucky if they can deliver a pot noodle each.
Plus of course there is the journey back, they won't get any supplies or fuel from Hamas (assuming they are allowed to leave). So I guess they will have to go nicely to the Israelis to see if they can help them out.
Its all Tik Tok driven virtue signalling with stuff all thought on the practicalities.