Are head support pillows required for prams? If so, until what age?

Red Nose does not recommend the use of head supports in a pram.

Red Nose does not recommend positional products such as anti-roll devices and items that fasten a baby into a sleeping position. Products that restrict the movement of a baby or a baby’s head should not be used.
This is because there are no Australian Standards for these products and case studies have shown that these products can be unsafe.
https://rednose.org.au/article/is-it-safe-to-use-products-designed-to-keep-baby-in-a-particular-position

Not all products sold have safety standards, particularly for sleep, in Australia.
https://rednose.org.au/article/baby-products-you-dont-need
https://rednose.org.au/article/baby-safe-sleeping-products