Yes making career moves from one technical field to another can be difficult - I hope you manage to find somewhere that'll take you on without putting you over a barrel.

I've found that it entirely depends what level of embedded development you want to enter - for instance I mainly work with C++ and MSQL databases on our platform - because our main device runs linux this makes sense. But other related products that we sell run on bare metal and are written in pure C.

Having a strong knowledge of C will most certainly get you far in this field, but perhaps learning the ins and outs of C++ wouldn't be such a bad idea if you have the spare time - the more niches you can fit in the easier it will be to pick up that job you really want.