Nunjucks nested variables

Are nested variables possible in Nunjucks? I need to be able to store a string in my database containing Nunjucks variable but it does not seem to work. Here's an example of what I need to be able to do:

dict = {
name: 'John',
lastname: 'Smith',
greeting: 'Hello, my name is  '
}

And then be able to do

<span></span>

but it outputs this:

'Hello, my name is  '

The reason i need it this way it because I have a database with some description templates with holes and i have a database with values and I need to be able to combine them. But it is not always the same values so I cant hard-code them.