How can I effectively prepare for unexpected technical interviews that expect me to design a feature and have a working solution ready?

I recently had issues with management at my company and, out of frustration, changed my LinkedIn status to "Open to Work." I saw this as a chance to practice behavioral interviews, as Alex suggested in his course.

After completing some behavioral interviews with recruiters, I’m now scheduled to speak with hiring managers next week. Two companies have moved directly to the technical round based on my recruiter conversations. Most of these interviews are expected to happen over the next two weeks. I did not expect to get any technical interviews because I thought I wasn't good enough. But somehow it worked out better than I expected.

Here’s what I found out about the technical interviews from a follow-up email that I asked :

Both are live sessions.

The first company, which builds secure financial systems, provided this detail:

- "This is a filesystem design question combining design and live coding. The expectation is to present a complete solution, moving beyond pseudocode. Develop an approach/logic that can be fully implemented within the allotted time." - TypeScript & Node.js

The second company, which works in the distributed systems space requires a live coding assignment in Golang but gave no specific details.

I'm unsure how to best prepare. These aren’t straightforward like LeetCode problems, and there's no information on which libraries or resources to use. I haven’t done system design interviews before, and these companies expect a working coded solution. I've been attending system design sessions and group discussions with Taro, but live coding a feature is new to me.

I've done take-home assignments before, where there’s ample time to prepare, but this will be my first time coding a working component from scratch in a live interview. The pressure is higher since someone is constantly observing. I could treat these interviews as practice, but I don’t want to waste these opportunities. There's no guarantee of another chance, and I want to do well. This experience will be invaluable, and I don’t want to regret not giving it my best.

I was also wondering if I should ask more follow-up questions on the specifics of the technical interview like libraries to use, existing examples, resources to practice, etc. Is this too much to ask or is it fine?

Any guidance on preparing for these interviews would be greatly appreciated.