> we'll also do interviews that are one-on-ones with engineers on actual issues that they're facing.

Be careful with this approach. If you're not paying candidates for their interview time, you're not allowed to use their work. Big companies go to great lengths to demonstrate that the entire interview is for the purpose of a hiring decision and nothing more. This is to limit liability. Your approach is very dangerous for your company and if an unhired candidate's idea shows up in your product, even if you arrived at that result independent of the interview, the candidate has a strong case against you in a lawsuit.

If you're doing interviews like this, be sure you've discussed all the nuances with your company's lawyers.