My wife (90) has dementia, blindness, loss of function of right extremities. Any suggestions to help make her life more meaningful?

Music was the only thing I found for my mother. And even though she couldn't take part mom did like to be in the common area with the other residents because she felt comforted to be around other people.

What about her sense of smell and touch? Here are some ideas:
Would she like aromatherapy?
Massage her hands/feet
Let her fingers play with a fiddle apron (little gadgets and things are sewed onto it, and she can wear it)
Does her facility allow pets? Maybe the farm girl would like to hold a cat or dog. If a real one isn't possible, I saw a stuffed animal for sale online that was weighted and had a "heartbeat" from the Alzheimer's Store. (https://www.alzstore.com/perfect-petzzz-cavalier-king-charles-p/0606.htm?gclid=Cj0KCQiA5NPjBRDDARIsAM9X1GJAT9cY7j5JBYe_yxWgL2TUemCYCUfmRQpDe71-0QjboC5NBaDcHbcaAtnzEALw_wcB)

That might bring her comfort. Good luck.

She can also make wonderful music of her own, there are string instruments available that may be plucked and strummed and sound lovely. Try a google search.
I’ll post some sources within the next few days.

Oh, I feel for your poor wife. My Mom lost what was left of her poor vision last year after an optic nerve stroke. She also is wheelchair bound. I struggle to find things she’s able to do but as cwillie has mentioned she’s able to sing along. She used to play the piano and I have a game called Piano with Songs on my iPad. You just play the red key and it sounds just like a piano or organ. She used to be able to do it herself, but now I hold her finger and guide her hand. There’s old folk songs and some hymns on it that she might remember, or maybe you could find hymns online you could sing with her. There was an news segment last week on the huge benefit singing has on dementia, so I would really encourage you to try something.
Other ideas I”ll just throw out to you, maybe they will spur an idea. I sometimes ask her to fold her nightgowns to “help” me. I have some old funny letters that her brother wrote to her when he was in the service during WW2 and I read them to her. Sometimes I read happy stories out of the newspaper (if there are any). I also bring the seed catalogs in and I ask her to help plan my flower and vegetable gardens. I read the descriptions and we talk about how flowers would look together or what veggies to plant.
Also I have made sure to gently let the other residents know that she’s lost her vision, so she will not be able to start conversations with them, and they are welcome to initiate a conversation. Also to cut her some slack when she may ask many times “where am I” or “where am I going?” They have become very supportive. I do wish that there were more activities there for the blind or visually impaired. You might mention it to the recreation therapists there to help you brainstorm ideas.

My heart goes out to you. Gosh she is lucky to have you, and we are lucky to hear from you.

Audio books. Music on CD. A radio? Someone to read to her?

OP I hope you stick around. We are enriched by your being here.

I just thought of something else... the therapists have an activity called grab bag. They put all kinds of small items in a paper bag and the residents have to close their eyes and reach in, bring out an item and guess what it is. That might be something you could try.

Take her out to the mall and let her touch and hold different fabrics. Go to the botanical garden or even Home Depot to smell the flowers or a bakery to smell and taste fresh bread. Go to a concert or bring her recorded music - composers and songs that made her feel happy when she was younger.