One good option is to intern somewhere. We have a great software engineer who started as a PHD student in Chemical engineering. He found that he was interested

One good option is to intern somewhere. We have a great software engineer who started as a PHD student in Chemical engineering. He found that he was interested in software development in the course of his work modeling CHE stuff. He started with us as an intern and then we offered him a SWE position. It’s been a year since he came on full time and so far everyone seems happy. We offered him the flexibility of ~day a week to finish off his PHD until he graduates. Good luck!