At our education setting we allow children to sleep outside, under the veranda, and under the shade of trees. Would this be considered good practice and are there any restrictions or best practice advise around temperature of outside sleeping spaces?

Red Nose recommends the safest place for baby to sleep in is their own sleep space (eg cot or bassinet)
https://rednose.org.au/article/what-is-a-safe-sleeping-environment

Once baby/toddler is showing signs of attempting to climb from the cot, they need to be moved to floor bed/mattress.

Check also what advice ACECQA & Local State Regulator require in relation to sleep environment for all children
https://www.acecqa.gov.au/resources/supporting-materials/infosheet/safe-sleep-and-rest-practices
https://www.acecqa.gov.au/sites/default/files/2024-08/PolicyGuidelines_SleepRestForChildren_August2024.pdf

What age of children are you referring to?
What surface are they sleeping on?