The latter of these modes has been created by Harmonix, who is the developer behind the Rock Band series. With Harmonix being at the helm of the project, IGN recently asked Epic EVP Saxs Persson and Harmonix studio director Alex Rigopulos whether there would be any future support for Rock Band instruments.
"Not at launch, but it's very much a priority for us to support instrument peripherals in the game," Rigopulos said. "It's something that we're actually already actively working on. We don't have anything specific to say about it yet, other than it's coming."
The Fortnite blog does note that functionality for these instruments will be arriving at some point in 2024, so players shouldn't have to wait too long.