He should also consider metal alloy 3D printing suppliers, the guys who make the 3D printing machines or the companies that provide printing manufacturing services. They pioneer new alloys and the latest tech for space materials. Many rocket engine components are 3D printed now with advanced alloys, and it's a lot of new cutting edge material science. Companies in this space are developing new alloys and capabilities all the time.
Or some kind of print manufacturing engineering role at a rocket engine manufacturer or a space company. Here are some possibilities: SpaceX, Relativity Space, ABL Space Systems, Blue Origin, Ursa Major, Launcher, Impulse Space, Varda Space…
Here's another one additive manufacturing company to look at:
https://www.addmangroup.com/process-material/metal-additive/In the alternative energy space, there are a ton of climate tech start ups that could be a good fun start to a career, although much of the "climate tech" is focused on carbon removal, there are a few energy startups looking at energy storage, nuclear energy, or geothermal energy. Googling climate tech energy start ups, or searching through the portfolio companies of climate VC funds will turn them up. Two example companies: Radiant Nuclear, Antora Energy,