I'm in my 40s too. I haven't switched roles in ~4 years, and probably won't for the next ~4, 5 years. But I have always painted and drawn as hobby. Seriously considering trying that for a short time during a sabbatical or -- more likely -- find a job as contractor from Mon to Wed, and spend the rest of the time drawing and painting.

If you are concerned about employability then I think going back to school or investing in a masters or some technical courses could be interesting. Or even moving to coordination/leader/engineer roles?

But if you have a hobby, maybe you could consider trying something different like either doing it in parallel, or maybe combining with engineering. e.g. I'm considering something like Blender3D + drawing using Grease pencil. Blender can be programmed with Python too, and this way I'd combine two things that I like.