Most of my clients tend to be Medical Device startups, but I did have a really long relationship with a major food manufacturer. While it makes sense for them to hire full time software engineers for some of the work, they always have a hard time finding device driver experts. Also they tend to attract less experienced engineers, so having me on board helps to manage and mentor their team. And I'm generally the one laying out the architecture and breaking the project into smaller parts so their engineers can implement it.

If you want to break into consulting, you have to figure out which field you want to be in. I'd avoid anything that has a boot-camp available for it, that's a race to the bottom. Then you need to get at least 10 years experience working in the field, preferably at a variety of companies, and make friends and business contacts at each place.