An optimistic take is they may be keeping a bit quiet on the details to avoid competition? Some results "first private fusion company to heat a fusion plasma to 100 million degrees Celsius" from their Trenta prototype and Altman says "...they and their team have built a generator that produces electricity. Helion has a clear path to net electricity by 2024..."

The design is quite interesting - twin electromagnets shove plasma at a million miles an hour into the middle chamber and then hopefully fusion flings it out again pushing back on the currents in the electromagnets and producing electrical output directly. Bit like a petrol engine where the piston / crank compress the mix and then after ignition it shoves back harder adding energy to the crankshaft.

https://www.businesswire.com/news/home/20210622005366/en/Hel...