I have been using my own harness for quite a while now and giving it constant and continuous updates and improvements. It is optimized for use with local models but can also use any API that I have an account with too when the desire arises.
I've only implemented support for one provider at the moment, but it is structured in a way where I can add support for any other providers or local models. It feels good to not be locked into any one company's models or harness.