I haven't done a deep dive on the technology, just a brief overview. From my understanding, the rock is vaporized and the gases are sucked up out. I believe it is a start/stop process, not continuous. Dig a little, suck out the gas, check the integrity of the hole, then start again until it reaches the depth it is aiming for. The sides of the hole are apparently hardened into something like a glass tubing. They claim they can use the existing fossil fuel industry infrastructure and workforce as well. Hopefully this isn't a fly-by-night idea.
Seems like there would also be Lunar and Mars applications to this kind of tech.

Neil DeGrasse Tyson shared this information posted on it.

US Engineers Test Millimeter Wave Drilling for Deep Geothermal Energy

American engineers successfully tested millimeter wave drilling technology to access ultra deep enhanced geothermal energy reserves.
Researchers at the Massachusetts Institute of Technology utilized high power gyrotron oscillators to vaporize solid granite rock using directed electromagnetic energy. This innovative thermal drilling technique completely melts the subterranean formations without requiring heavy mechanical drill bits, allowing operators to reach extreme depths where massive geothermal heat continuously resides today.
Unlike traditional geothermal systems that rely on naturally occurring hydrothermal reservoirs located near tectonic fault lines, this specialized deep drilling method works anywhere globally. The unique millimeter wave beams easily penetrate incredibly hard crystalline basement rock, unlocking virtually limitless baseload thermal energy resources directly beneath standard commercial power plants.
Extensive laboratory testing demonstrated that these advanced prototype systems successfully maintained stable borehole walls at temperatures exceeding five hundred degrees Celsius. The localized melting process naturally forms a smooth impermeable glass lining, completely eliminating the risk of groundwater contamination and ensuring exceptional long term structural integrity for the well.
National energy authorities are currently planning extensive field trials to integrate these deep thermal wells into existing municipal power grids. Deploying standardized deep geothermal arrays will heavily accelerate the complete decarbonization of global electricity networks by providing a highly reliable and completely weather independent alternative to fossil fuels.