I don't think scientists want research software engineers. PIs typically like to assume any and every role on a project, including software design. They don't like handing things off and letting people build modern, best practices software. You start talking about source code control, package managers, a language used in industry that they've never even heard of and don't care enough to learn about, etc., and you just get asked "why can't you just write it in Python or C because those are the only two things I'm remotely familiar with and zip it up and put it on a USB drive?". Heaven forbid you actually want to do something novel, no matter how enabling it could be. I have been continually inspired by Bret Victor's
Seeing Spaces talk and have always wanted to build such a system described for a lab, but unfortunately, it was really hard to get anyone interested much less excited by such an idea. Scientists are far more institutionalized, conservative, and myopic than they admit. Physicists don't even use the proper word for code. They call it "codes". (I've seen in first-hand, in research papers, and in published books. It's endemic.)
I've literally sat in meetings trying to get access to scientific projects I'm interested in and applied for jobs even at the university I already worked at in similar capacities, and yet, it's filled with PIs just wanting grunt labor (i.e., what they're used to from graduate students) to build things that they understand or you absolutely never hear back or the pay is a third of what you already make. And then there's pockets of software people in this niche world that only want to do things their way, because that's all they've ever done, and they can really be quite obstinate. They're like this massive pillar you must somehow work around.
I really, really, really like writing software in scientific contexts, but it's such a quagmire. I'd like to return to that world some day with the lessons I've learned outside of it. Software in support of an interesting domain or context is just really fun. I've also tried getting a job at an architecture firm that had some very neat ideas for building out a tool, but the response was basically the same as described above.