Perhaps military style reactors designed for propulsion loads would be a good match for balancing renewables on the grid as an alternative to natural gas peaker plants

Military style reactors use highly enriched fuel, often near weapons grade. That's an acceptable thing for a carrier or submarine that's also full of things that have to be continuously secured, like nuclear weapons, but is a big challenge for a small modular reactor scheme. Most of the stuff proposed in recent years for small non military reactors has focused on a middle ground of partial enrichment that's more approachable.