It's not unusual for a 10 month old to feel reassured by your presence and panicked if he thinks you are going to leave him. I'd bring the cot back into my bedroom, if it's not already there.
It's an interim to getting him used to sleeping in the cot, but with you there next to him.
Then I'd do all settling with baby in the cot. I'm not a fan of PUPD, it must be perpetually frustrating for the baby to feel comfy and secure in your arms, then be made to seperate over and over again.
In my view much better to gently teach him to feel comfy and secure in his cot to go to sleep.
Still stay with him, lie in your bed next to him. Lots of eye contact, care, compassion, shushing, patting.
Continually lie back down and dumny reinsert with every time he tries to get up. A firm hand on the chest helps with reassurance and also to keep baby still.
Then, over time, slowly and gradually reduce the level of reassurance he needs to be able to go to sleep in his cot.