They have follow up government studies to develop the superconducting magnets and other components.
They are using radio frequency heating to reach fusion conditions. They need helium 3 which is scarce. There is enough helium 3 for some small space missions but would not be able to scale until there is more helium 3. Also, the cost would not be initially competitive. They are looking at high value niches.
It is a lot easier to make a fusion rocket versus a fusion power plant. Shorter pulses for fusion for propulsion is simpler than constantly generating power.
Princeton Satellite System has novel antenna configurations.