You are a good, good person.
Maybe there is a Lego Tardis set you could send him. Or a jigsaw puzzle of a Tardis. I’m sure Mumper building experts like oopsie or paintcharge would have some good ideas.
Sending him things occasionally will directly do him a world of good but also inform the assisted living home staff that he has friends who care about him, who are staying in touch with him and are watching out for him. You’d be amazed at how that can improve the quality of care he’ll receive.
Again, you are a good hoo-man.