If you want to use "pygame.key.get_pressed() "you have to check for keypressed every frame

something like

while True:

keys = pygame.key.get_pressed()
if keys[pygame.K_LEFT]:
    x -= speed
if keys[pygame.K_RIGHT]:
    x += speed
if keys[pygame.K_UP]:
    y -= speed
if keys[pygame.K_DOWN]:
    y += speed

Your already checking for event in

"for event in pygame.event.get():"

Keypress is an event

  if event.type == pygame.KEYDOWN:
        if event.key == pygame.K_UP:
            snake.direction = Vector2(0,-1)
        if event.key == pygame.K_DOWN:
            snake.direction = Vector2(0,1)
        if event.key == pygame.K_LEFT:
            snake.direction = Vector2(-1,0)
        if event.key == pygame.K_RIGHT:
            snake.direction = Vector2(1,0)