Widow and orphan control is an insanely difficult and non-trivial task. I spent about three months on this in the past, and even took out a tech support incident with Apple and got help from an Apple text engineer - all to no avail. The upshot of all of that work was the “Keep with Next” feature, nothing else. The problem is that you aren’t just fixing the current container (page) - pushing down a widow - but you also have to look ahead to the next container for orphans, and then re-layout the previous container if necessary. It turns into a recursive mess. Add to this the complex code required by end-of-page footnotes, which already has to tweak container space and make sure that, in reducing the text on the page to make room for footnotes, it doesn’t push to the next page the text associated with the footnote, and the job of implementing widows and orphans is now even more complex than it was when I last looked at this.
So, I’m afraid that this is unlikely to come any time soon, if ever. Out of interest, though, why do you want it? As you say, you can export to Word if you really need this. And I flicked through the books on my shelves - novels, mostly - and I couldn’t find one that had definite widow/orphan control. The vast majority had widows and orphans liberally throughout.
All the best,
Keith