Looking to buy a bassinet for newborn to sleep in overnight in parents room. I’ve noticed that they do not have standards like cots do. What are the best options? Are the rattan bassinets safe to use?

There are no mandatory standards in Australia for bassinets, as you have discovered.

Product Safety Australia & Red Nose have the following information:
As there is no Australian Standard for bassinets, we are careful to keep up to date with reports of accidents associated with their use.
To date, the most frequent accidents associated with bassinet use are falls and suffocation hazards.
https://rednose.org.au/article/bassinettes

Ensure the sides of the bassinette are at least 300 mm higher than the top of the mattress base.
Ensure it has a wide stable base and a sturdy bottom so that it won’t tip over.
Ensure the mattress fits well and is firm, smooth and no more than 75 mm thick.
If the product has folding legs, make sure it cannot accidentally fold during use.
https://www.productsafety.gov.au/products/babies-kids/kids-furniture/bassinettes

Have a look at these suggested guidelines (buying tips) from Product Safety when you are looking to buy a bassinet…........... particularly in relation to stability, height of sides & mattress thickness & firmness.