To get the route itself, remember how you reached each node (its parent), then walk backwards from the goal:

from collections import deque

def shortest_path(graph, start, goal):
    parent = {start: None}
    queue = deque([start])
    while queue:
        node = queue.popleft()
        if node == goal:
            path = []
            while node is not None:
                path.append(node)
                node = parent[node]
            return path[::-1]
        for nbr in graph[node]:
            if nbr not in parent:
                parent[nbr] = node
                queue.append(nbr)
    return None

graph = {"A": ["B", "C"], "B": ["D"], "C": ["D", "E"], "D": ["F"], "E": ["F"], "F": []}
print(shortest_path(graph, "A", "F"))