There are applications that can show the current space in the menu bar.
Spaceman shows all spaces and highlights the current space. It defaults to showing numbers and can also assign a three character label to a space.
WhichSpace simply shows the number of the current space.
I do not know if either will meet you need for indicating the space. I used to use Spaceman and recently switched to WhichSpace to save on menu bar real estate.
There is a thread on the forum to automate getting the focus mode. You might then be able to put the focus mode into the text string that One Thing would show in the menu bar.
Again, I don’t know if having this info in the menu bar would meet your needs.
Good luck and have fun!