Postscript is really easy to generate from shell scripts; I wrote a little thing that did labels for our (physical books) library.
Not sure what I'd use for alternative. I'm sure there are many little modules that would help. Or I could just install Postscript. But it's nice to have things with fewer dependencies.
Output of SVG in actual print can be quite unpredictable. Of course, I'd stick to a particular implementation, and just aim for it to come out right. Should be pretty simple.
Back when XML was the only way to go, there was a page-description language built on top. And it ultimately generates... PDF!
XSL-FO was a good idea, but it never went anywhere. Processors were costly and underfeatured, HTML+CSS ran circles around it. IIRC, XSL-FO didn't even have floats for a long time!
It's a pity that there appears to be little interest for page-oriented features of CSS: breaks, headers, footers, numbering, etc. Most don't work well or at all.
Not sure what I'd use for alternative. I'm sure there are many little modules that would help. Or I could just install Postscript. But it's nice to have things with fewer dependencies.