Today, it has integrations for Paypal, Etsy, Shopify, DHL and HBCI (no more copy and paste, finally) and basically covers the whole order cycle with minimal fuss and gives her a quick way to publish new products which she does a lot as fabrics come in / get sold out.
I guess that's not that useless but of course it simply can not be worth the time I spent on it.
Yet, I don't regret doing it in the least because for me it literally is a labor of love. Plus, I learned a lot doing it and I can go down crazy paths like this one time I made an android app to cut out the background of her product photos. Didn't turn out to be useful in the end but eventually I did use OpenCV via JavaCV for something else in the software.
Currently I am in the process of rewriting it in Kotlin / Multiplatform (JVM+JS) and again, I'm learning a lot and making the software a lot sleeker and more functional. That's not going to be worth it either, I am sure.
Anyway, I wish I had day job were I was in constant contact with users to built them something of tangible utility and value.