I am so sorry for your loss.
When one of my Rottweilers passed, his Lab/Sharpei friend stopped eating/drinking/ taking care of business. It was gut wrenching.
The best way I have found is to get another dog but that isn’t possible for everyone.
I have taken in rescues most of my life so getting a dog “five minutes ago” has never been an issue, but old age is now getting in the way of that.
Hopefully you are able and can find a somewhat younger dog as a companion to keep Nilla Wafer occupied.
If your love is Great Danes,please look at the Great Dane rescue websites. There are many out there who would be so grateful for a home such as you can provide
My sympathies over your loss and best wishes whatever you decide