The trick is not checking for leaves but checking for the Nones after the leaves, which also handles the case of root == None.
def find_path(node, seq, i=0):
if node is None:
return len(seq) == i
if i >= len(seq) or node.val != seq[i]:
return False
return find_path(node.left, seq, i+1) or find_path(node.right, seq, i+1)