[eschneider]

IMHO, it varies wildly from company to company. A portfolio is great and I'd expect some sort of general coding test. In general, if you can do the usual leet code tests (I know, but it's the world we live in...) can demonstrate a good knowledge of C/C++ and show you actually understand how pointers and memory work, you're probably hireable as a beginning embedded software engineer.

If you're looking for bare metal work (as opposed to embedded linux) being able to read and understand schematics is useful, though I've never had anyone ask for that in an interview.