Tab Completion – How to extend inline shortcuts in Fish Shell?

I'm trying to save some time in Fish Shell by putting a shortcut (nu) to extend the string:

my-username @ my-ip-adress: / home / my-username

What I hope to achieve is to enter:

scp some file nu

… then tab or space – complete the nu Shortcut to extend it to the string I have in my config.fish,

I have more use cases for this functionality, but Fish does not seem to handle it. It provides shortcuts, but they only seem to work at the beginning of a command. I can not get her to work inline. Any ideas?