It sounds really challenging and frustrating for you. There could be a few things going on.
Separation anxiety: Even though he's at nursery, the transition between sleep and wakefulness might make him feel insecure and he could be seeking comfort through the dummy or cuddles. This can be especially intense around 1 - 2 years old.
Sleep associations: If he's used to falling asleep with a dummy or being cuddled, when he wakes up during a normal sleep cycle (which happens every 45 - 90 minutes in babies), he might expect the same conditions to fall back asleep.
Over - tiredness: Sometimes, despite being active at nursery, if his sleep routine isn't well - regulated, he could be getting overtired. This can make it harder for him to self - soothe and lead to more frequent night wakings.
Environmental factors: Check if the room is too hot, cold, noisy or if there are any new items in his room that might be disturbing him.
To help, you could try gradually reducing his dependence on the dummy by only offering it at the start of sleep and not replacing it when he wakes. For the cuddles, you can start by soothing him while he's in the cot, gradually reducing the amount of physical contact over time. Also, make sure his bedtime routine is consistent and calming, including a dark, quiet and comfortable sleep environment.