Is this only for software engineering roles, or could it be appropriate for roles for YC's other styled companies (synthetic biology, nuclear reactors, etc.)?
Some of the companies presenting are hard tech companies like you mentioned. For example, Athelas (blood diagnostics), Inokyo / Standard Cognition (stores with cashierless checkout), volans-i (delivery service via drones). Those companies are all hiring for software engineering roles and also other kinds of engineering roles as well.
Additionally, if you need help finding a company that might be a better fit to your skill sets/interests, feel free to email me at ryan@ycombinator.com and I'm happy to do what I can.