You can get C++ OO without linking in a whole STL. IIRC it is the C++ equivalent of -ffreestanding in C. Given that popular toolchains like GCC and IAR offer C++ support to micro controllers as small as ATtiny 8-bit AVR micros, I don't see the necessity to reimplement C++ in a hamstrung C form.

I'm currently writing a binary parser library using C++ but without the STL. I'm able to use range-based for loops, zero-cost iterators, and other features without any dependencies on a C++ STL library. After optimization, the generated code is essentially what the C equivalent with all the boilerplate would compile down to. There are plenty of OS kernels written in C++, you just have to pick the appropriate C++ subset. ;-)

Regardless, I enjoy the stricter typing in C++ that generates essentially same code as C with OO tacked on but with less boilerplate.