Batteries and hyrodelectric storage are the only energy storage mechanisms for which we have any meaningful cost history.
You are already well aware of numerous alternatives. Insisting they are "untested" is not fooling anybody.
Are there any >1GWh thermal battery facilities? Remember the US uses 8GWh of electricity per minute.
I don't know about that, but for comparison, the "world’s biggest battery storage system" opened last year in California[0] at 400MW / 1,600MWh.
[0] https://www.energy-storage.news/expansion-complete-at-worlds...
My point was that GWh-scale thermal battery proposals would be competing with already existing (and possibly cheaper) chemical batteries, and that energy storage on this scale is not unheard of.
Even as a nuclear supporter I would welcome more renewables if we had cheap scalable storage, which no one has it seems. (at least no one pointed out such project in the entire thread)
But for much of the world what doesn't have this option, nuclear remains the most viable energy source.
Btw even the Sweden example uses nuclear for decarbonization of the grid ...