I actually thought of one that wouldn’t change him much at all and still help him out in 1v1s tremendously.
Allow his healing field to nullify stun effects. Let’s say if a doomfist were to uppercut soldier in his heal aoe, he would now still be able to fire his weapon or helix the doom for the entire duration of doom’s uppercut. Soldier would also be able to now aim/look in other directions, which he could not do before. The only thing that would remain from the enemy’s ability is the knockback, so soldier would still not be able to adjust his positioning because of uppercut’s momentum lock. It would be the same for wreckingball’s ground slam as well which would still knock soldier in the air but now he can attack without interruption.
It would help the team a lot too. It would make diving doomfists and wreckingballs actually try to wait out soldier’s heal field before they can go in and get out for free which they can basically do now.
let’s face it soldier gets wrecked by stun. now he can actually win fights or trade deaths more when dealing with roadhogs, brigs, mccrees etc