I’m just using a standard automotive 3 amp that fits the lund fuse panel I wired it into. Bought an inline that uses the same two blade 3 amp fuse for other unit back by kicker. That’s all I’ve used for last couple of boats with no problem.
The fuse is there to protect the wire and limit the possibility of starting a fire. There is no way that a fuse is fast enough to protect the electronics.
The power cord has some pretty small gauge wire but any fuse up to about 8 amps should work.