I think my grandparents canary needs help, what can I do?

This is my grandfathers bird that he got about a year or two ago, he ended up with dementia this year and hasn’t really been in a place to take care of “buddy.” What I want to know is how I can help take care of him. I know very little about birds but I think he’s way too big and needs his nails clipped. I’m pretty sure he’s only eating seeds and I would think he probably needs a more diverse diet? Any help and advice is greatly appreciated!!

This is my grandfathers bird that he got about a year or two ago, he ended up with dementia this year and hasn’t really been in a place to take care of “buddy.” What I want to know is how I can help take care of him. I know very little about birds but I think he’s way too big and needs his nails clipped. I’m pretty sure he’s only eating seeds and I would think he probably needs a more diverse diet? Any help and advice is greatly appreciated!!