Hello I Co sleep with my two year old on a queen size floor bed. Now that I am getting ready to introduce a doona I am wondering if it’s ok to use a normal queen sized doona for the both of us. Or would it be best to use a toddler size doona for him and my own blanket for myself? Thank you

Red Nose has no specific answer to this question in relation to bedding for a 2yo.
The only information we have in relation to a toddler sleeping on a floor bed is in our Cot to Bed brochure.
https://rednose.org.au/downloads/RN0407_22_Cot-to-Bed.pdf

I have also added link to Red Nose information on co-sleeping (it is predominantly related to babies less than 1yo, but may be of interest to you. - https://rednose.org.au/downloads/RN0493_23_Co-Sleeping.pdf

The general recommendation for bedding is to withhold pillows & doonas until a child is in/on a bed/mattress & over 2 years of age.
Sudden Unexpected Death in Infancy (SUDI - SIDS & Fatal Sleep Accidents) does not occur after 12 months of age (by definition)
However, there are some sleep accidents/injuries that may occur after 12 months including suffocation, particularly when heavy bedding is used for baby.
It may be less risky to use separate doonas - although many toddlers do not stay underneath bedding, so on cold nights it may benefit from an extra layer of clothing.