Maybe you can try this code
func _ready() -> void:
var list = [2, 3, 4, 5, 6, 7, 8, 9]
print( pick_rand_number(list, 9) )
func pick_rand_number(list: Array, amount: int) -> Array:
randomize()
list.shuffle()
var new_list: Array = []
assert(amount <= list.size(), "The number cannot be greater than the size of the Array")
for i in range(amount):
if new_list.size() <= amount:
new_list.append(list[i])
return new_list