If you were having the same problems with a different time, it may well be behavioural then. Do you think he would respond to something like a sticker or a stamp on his hand as a reward if he stayed for some quiet time without making a fuss? Or is he too little for something like that?
Am thinking how to get him to "like" bed- Alex loves to come in our bed and snuggle under the duvet and pretend to be asleep (- he makes snoring noises, v cute) so I encouraged this by bringing him into our bed in the morning, watching a bit of tv, enjoying just laying there relaxing so he could see how much *I* like bed, getting him ready for bed on our bed, and letting him snuggle there, playing in bed with him and also pretending to sleep; then giving him his own duvet was so exciting for him, he is a big boy now, etc etc. At bedtime he gets into bed and sits there like a big boy with his beaker of milk and has 3 stories, then 3 lullabies then lays down and lights out. He also takes a cuddly toy with him to bed now (this is VERY new as previously he would just play with it and not sleep so toys were not allowed) and - crucially for him- he is allowed to choose himself which cuddly toy it is from the basket before he gets into bed.
I think treating him not like a baby any more in relation to sleep has really helped. It's weird, since he turned 2 he seems to have "suddenly" grown up, and my friends say the same of their lo's too.
Don't know if any of this will be helpful, just thinking out loud for you, really