The way I'd summarize is that you want to give something back to the world/your working group, and since you're fond of programming you're proposing writing a tool.

I like the idea, I think it has merits but I can't judge since I'm not qualified in your field. I'd just say, if you're a specialist there's a very big chance someone did an open source very similar to yours but not exactly and it's likely you're not going to find it because it was short lived.

I'd also say that writing software is the modern version of"write a book" in the adage "plant a tree, write a book". It's your unique way of expressing your ideas in a very specialized, niche, knowledge space, and sharing with other people less specialized in the area you are an expert. So there's merits in itself.

Re your boss's goals and expectations, no idea, but if you don't have his support it means it's a personal project, not a work/academic one.