Hello Madarina,
Could you please let me know how much delay you have experienced while sending push to users. It will help us to provide better support to you.
As of now settting a priority on Push Noitifcation message is not avaiable. We have recorded your request of providing this feature through API, so that it will help you decide the message priority. We will update you very soon regarding the timeline for this feature.
Regards,
Himanshu Sharma