There's not much new info here since the last time the project was discussed. The first two comments here link to informative videos about how the reactor works: https://news.ycombinator.com/item?id=24629828#24634733

News since then:

CFS has now raised $1.8B

They have demonstrated a full-size magnet with a field strength of 20 Tesla

They have started construction on the new SPARC reactor facility.