There are a few of us alone who will be on here so you will have company OP even if it is the stranger on the internet type.
But why not plan your perfect solo day?
Get one of those small bottles of cava/prosecco/champagne and start the day with a long bath and a glass of bubbly.
Have something nice for breakfast, smoked salmon and scrambled egg?
Borrow a dog to take for a walk.
Put on a nice outfit and cook your favorite food be that curry, chips, shepherds pie or just a load of cheese.
My grandmother used to choose to spend the day alone, she had 'open house' Xmas eve so people popped in all day and she didn't have a tree but would buy some nice flowers.
I like the idea of a project, I learned to pick a lock a couple of years ago, not for any reason other than I wanted to know how.
Or is there a beauty treatment you are overdue, a face mask, a deep misuse to your hair?
Save your presents to open in the evening and finish the day with hot chocolate and a dash of the spirit of your choice, vanilla vodka works well.
Oh and the best thing about being alone, you can plan all that but if you want to you can just stay in bed.