Scratching and finger sucking 13 month old

I’m not sure if this is the right place to post this question, but I’ve found myself pretty aligned with a lot of the guidance on this sub, so I thought I’d start here.

I’m a first time Mum to a little boy, about to be 13 months. Since he was a few months old, we’ve been cosleeping. I generally lay down with him for his naps (and either nap or read / listen to podcasts etc) and then do similar at night time, though I sometimes hop up once he’s settled and then rejoin later. All this to say, a vast majority of his sleep has been in my physical presence.

This has been fine, but I do slowly want to transition him to sleeping alone more. There are nights where I feel that we are disturbing each other, and I’d like to be able to sometimes be free during his sleep.

He currently has two ways of resettling himself when he stirs (before crying or truly waking up). The first is sucking his fingers (fine). The second is scratching the bejeezus out of the back of his neck (not to my taste). Despite short nails and ointment on his neck, he can easily break skin and really irritate the area doing his half asleep scratching. The obvious, and somewhat effective, solution is to have mittens on him when he’s asleep. This is fine, except that it means he can’t suck his fingers. When I’m in bed with him he can have a short feed instead but if he’s on his own he tries to suck his fingers, can’t, then scratches at his neck for a bit before waking up indignant and outraged. When he’s cuddled with me I do interrupt the scratching, even with mittens, and then he relies on the feeding to resettle.

The spot he scratches is essentially topical eczema, and we are treating it. The doctor isn’t concerned about it as a standalone issue. Given that he pretty much only scratches like this when he’s tired / soothing himself, I’m inclined to think that it’s not causing him terrible discomfort.

We’ve tried a dummy a few times over the past year, with very limited interest from him. He usually spits it out pretty quickly, and then either totally ignores it or wants to examine it in forensic detail, which isn’t conducive to sleep either.

Am I missing something super obvious I could be offering him? Is there a way to introduce or encourage him to use other soothing techniques? Am I massively over policing the neck scratching? I feel like I’m shooting myself in the foot by blocking off the finger sucking, but I’m not okay with the neck scratching.