My day job is engineering in systems that kill people or cost billions of dollars if they go wrong.
I'm never going to ask you to code something on the fly other than hello world, a loop to print 0..9 and maybe a recursive function to print 0..9. You can't think deeply enough about a problem in one hour, or one day. I will ask you a lot of questions about what you will do, how you will do it, and what the possible problems and mitigations are.
A portfolio that you've worked on is great because I can find the worst code in it and ask why it's there, what the trade offs of putting it there were and how you would fix it if you had infinite time.