Without knowing the details of your recovery (I hope all is well), I’m leaping here, but I actually strongly disagree with above.
Target training is a hands off technique, which by its nature is applicable to distrustful birds, and develops the communication that facilitates bond building. So long as he’s healthy and you find the reward he loves, there’s no reason you can’t do it now. He’s can relatively easily be desensitized to the target object (which can be anything! A pen, wooden dowel, strip of fabric, whatever you want!): depending on the bird, it could be as little as 3 clicks of the clicker or maybe two days at most. EASY.
The applications to target training are endless: moving the bird around, desensitization to an object, teaching it to turn/spin, to name just a few.
My question is, is he fearful of YOU right now after the medical care?