Hello Hellboy,
It seems this dataset is not included in your database. You will encounter this in many cases when making LCA's.
There are a few ways to deal with this. In your case I would use secondary data, either directly or by modelling the secondary data. I found this:
https://www.spp.org/about-us/fast-facts/ which is the grid composition of US-SPP of 2022. If you model your own process, with the correct proportions, it will give a decent approximation. If you need extremely precise data, i would call them, and ask for the direct information you need. This would be information like loss through the grid, loss in production, loss through transformation, etc.
However, just modelling the above will give you a good approximation. Good luck.