Is it possible to fulfill multiple orders using a single goods out note?
No. Each order will have (at minimum) one goods out note.
You will need to combine the orders before fulfillment in order to create a single goods out note for all the items.
As it's not possible to merge sales orders, you can do this by adding all the items to a single sale and processing that.
Note that if the sales orders downloaded from your marketplace or web store, you will have to manually mark the sales as fulfilled in the relevant channel.