20 months old taking forever to fall asleep

My almost 20 months old has been taking 30+ min to fall asleep for both nap and bedtime. Nap is however worse as he will be awake still an hour after putting him in the crib and starts calling for me. During that hour, he hangs out and rolls around in bed. Looks like he is trying to sleep but struggling. He has been complaining about sleep sacks and saying “feet stuck” even though his sleep sack is large and not tight on him. I don’t know if that is playing a role. Usual schedule is wake at 7am, nap from 1-2:30 or 3 max, and in bed at 8pm. Sleep trained and usually falls asleep independently for both nap and bedtime, without crying and sleeps through the night. He also seems tired and ready to nap when I put him in the crib and doesn’t fight it. And I don’t feel I can make that first wake window longer than 6 hours. Help please!