Alternative to sleeping bag

[Millenial]

My 18 month old is a terrible sleeper and wakes multiple times every night. My DM has suggested that maybe he feels restricted in his sleeping bag as he does like to spread out.
Due to him tossing and turning and usually waking at the opposite end of the cot to which he fell asleep, I don’t think it’s time for a duvet or similar.
So, is there any other option that I’m missing other than sleeping bag or duvet that would be suitable for 18 month old?

We had these

www.jojomamanbebe.co.uk/glowinthedark-space-dog-print-2-5-tog-sleep-snuggler-e7922.html

Seemed to do the trick

I used sheets and blankets, and then a duvet. DC learned how to pull it back over themselves if they got cold.

We use a duvet, I tuck in well and he will often pull back over himself

Both of mine used to roam all over the cot until we introduced a pillow at around 18m. We had (and still use) the thin little toddler pillows you can get from IKEA. At first they used them with their sleeping bags, which kind of helped to 'anchor' them in place in the cot. Then we swapped the sleeping bag for a toddler duvet a few weeks later.

Both slept better under the duvet - it's far cosier.