Hello, I have an almost 2 year old who is sleeping in a toddler bed currently in a grow bag. I would like to introduce a pillow to her once she has turned 2 years. Is this safe to do so? If so, what type is pillow is the safest?

Many toddlers in a bed may not even stay sleeping on a pillow, or sleep under bedding so they are often unnecessary.
Red Nose has the following general information about pillow use.
Pillows are not necessary for baby and increase baby’s risk of sudden unexpected death in infancy including SIDS and fatal sleep accidents
Red Nose recommends delaying offering a pillow until baby is over two years of age and is no longer sleeping in a cot or portable cot
https://rednose.org.au/article/pillow-use

Red Nose does not recommend any specific type of pillow to use.

It might also be a good time to cease using a sleeping bag for your baby.
Do not use a sleeping bag once child is out of the cot & in a bed. This helps to reduce the risk of falls once they wake & try to get up & walk.
A child wearing a baby sleeping bag and not confined to a cot is at a higher risk of slips, trips and falls and of being injured. The child must be actively supervised and the sleeping bag removed as soon as the child wakes.

https://rednose.org.au/article/transitioning-from-a-cot-to-bed