So I suppose this is the way to go for now? Are there plans to add support for nested typed arrays in the future?

var _adjacency_matrix: Array[Array]
func setup(p_size: int) -> void:
size = p_size
for i in range(size):
_adjacency_matrix.append([])
for j in range(size):
_adjacency_matrix[i].append(j)
func populate() -> void:
var n = 0
for i in range(size):
for j in range(size):
n += 1
var vertex := Vertex.new()
vertex.label = str(n)
_adjacency_matrix[i][j] = vertex