Touya is alive and lock in to know why (delusions' final boss) :
in Shoto's point of view while talking about him the flashback of Touya is his regular self, it's not blurry or pixelated in the regular mourning ways and he doesn't view him with the burns between the cheeks and eyes or even in the machine, so he's probably healing. + he's genuinely smiling, but Shoto has never seen him smile like that, so that means they're talking and getting close which brings me to the next point
I really like this one interpretation where Shoto is praying at Touya's altar (which they had since he was 13) for his health. this thing isn't only an altar, but a butsudan, and you pray at one twice a day for luck, health of your family members AND ALSO for passed away. but they had it for a while and it would be just weird to destroy it? so they probably kept it and that's where he meets up with Touya to talk
Touya has defied life and death odds during the coma, after the coma, and after the final fight, he's just THAT bitch, he's alive, thank yew ‼️
you know what? hell yeah i just stood up and applaud yup no need to convince me anymore i believe u touya is 100% alive yaaayyy everyone say thank you anon!!!!