I think you're focusing too much on punishments and not enough on what he is trying to communicate with this behaviour.
You say he has been assessed by an educational psychologist for ADHD and ASD. Educational psychologist are not qualified to rule out ASD. I don't know about ADHD but I suspect the same applies.
I have two DDs with high functioning ASD, Asperger's Syndrome, and the behaviour you are describing sounds very familiar to me.
I would take him to the GP and ask for a referral to CAMHS or a paediatrician for a neurodevelopmental assessment.
In the meantime, think of your DS as being emotionally younger than his age. He may be unable to understand his own emotions or the root of them and find it difficult to explain how he is feeling verbally.
He might have been smirking because he was genuinely unable to control his facial expressions and may not even know what would be an appropriate one for that situation.
He sounds confused, overwhelmed and very angry with the world. He needs you to be on his side, helping him to understand his own emotions and find more appropriate ways to express them. Meltdowns where an 8 year old trashes his room like that are likely to be the result of a lack of control and my DD2 always felt devastated and angry with herself when she did it at that age. She now uses a punchbag instead.
If he has ASD, tidying his whole room may feel impossible. Google executive function to help you understand why long complex tasks like this could be a problem. My DDs are both highly intelligent but could not cope with tasks like this at that age.
If he can't understand or describe his emotions, it would be very hard to be asked to talk about them. Maybe that is why the play therapy isn't working. Try labelling his and your own emotions for him, e.g. I can see you are feeling upset because you can't have any sweets. It must be disappointing. I feel sad about it too.
Lots of children with neurodevelopmental disorders like ADHD and ASD rely heavily on the down-time they get from using screens. They are socially undemanding, predictable and easy to control. When the world feels scary and erratic, they offer a very attractive respite. Try not to use removing this support as a punishment. When my DD1 was really struggling, CAMHS told me to make sure she was still able to do things she enjoyed - horses was her thing - because it was a rest from feeling rubbish about herself.
When children are struggling like this, sanctions are often ineffective and counter-productive. They erode the child's self-esteem further and create more of the negative emotions they struggle to manage.
Try to spend time with him building his self-esteem. Let him know when he does things you appreciate, join in the activities he enjoys and try to communicate that you are there to listen and help. Shoulder to shoulder is better than face to face so sitting next to each other in the car or doing a jigsaw together can help with communication. Don't talk about what you don't like about what he does. Ask him what he thinks about things and what he finds hard.