I'm belatedly learning this lesson (you'd think I'd have caught on earlier in my career) I very much want to stick to small young startups in future, but there's less demand for tech writers there.
Either you freelance and work for multiple companies or you add other skills to your portfolio.
For example
- creating videos of your articles/docs
- hosting events like hackathons or meetups
- developing libraries or integrating the product with popular platforms
Good technical writing is especially important now. I guess you can try to train bots on the codebase itself, but unless that's pretty well documented, I wouldn't expect as much from that as training them on good technical documentation.