The odds of being able to change this company are quite low. So, you'll need to make a choice. Do you want to stay until it starts to hurt your health, or do you want to leave and risk long term unemployment?
If you want to stick it out, you might need to take control of the team. In that case, I'd start by figuring out why the developer is having problems maintaining 10 microservices. Is it death by agile, is Go the wrong tool, or is it a case of massive technical debt? Or, was the whole project built by a burned out developer?
Once you figure out what's going on, you'll have to be open and honest with your CTO. Maybe your CTO needs to back off? Maybe your CTO needs to get more involved and start writing code? Maybe the other developer just isn't cut out for the company?