Is it an either/or situation, though? Part of the appeal of hydrogen is it can be a useful way to handle excess generation in an economic way-- whether via nuclear at nighttime when demand drops or when renewables are overproducing during particularly sunny/windy days

Hans, you made my day. The nonsensical "saving energy by wasting energy" movement around here can sometimes get anyone who understands a little bit about physics down.

Sure, Hydrogen from electrolysis is inefficient.

But any real-world energy transition is going to take 30 years due to the amount of infrastructure involved.  Electricity is only one of three major energy sectors.  If we wait for complete decarbonization of electricity before beginning the decarbonization of transportation and heat (i.e. H2 from excess clean electricity), that just makes the whole transition take 30 years longer.

We know that part of transportation and part of heat will be resistant to electrification.  We should start building the infrastructure to decarbonize those sectors now.  Hydrogen can be part of the solution, as can ammonia fuel and district heat networks (with electricity, this constitutes the complete list of practical carbon-free energy carriers).

We need the environmental movement to embrace hydrogen from fossil fuel with CC&S (as a bridge technology), warts and all, and start building end-user infrastructure.  Otherwise deep decarbonization simply won't happen in our lifetime.