Yep. That's what I do. Just API keys and you can switch from Opus to GPT especially this week when Opus has been kind of wonky.
I'd rather switch to OpenAI than give up my favorite harness.
For me it's $0.8/kWh during peak, $0.47 off peak, and super off peak of $0.15. I accidentally left a little mini 500W heater on all day, while I was out, costing > 5% of your whole month!