Merge svg files into PDF

I have a directory of about 1000 svg files in svgz extension, which resembles a textbook. An example of the svg files can be found here.How would I merge the files into a PDF while preserving as much quality as possible?

As you can see in this image, the PDF rendering of the svg is incomplete, but a quicklook view or opening it in chrome renders it completely. Google Drive preview also does not render it completely.

Solution 1:

Based on nohillside's answer and Matthieu Riegler's answer, this is my solution:

cd /
for i in /path/to/folder/*.svgz
    /Applications/Inkscape.app/Contents/Resources/bin/inkscape $i --export-pdf $i.pdf
end
cd /path/to/folder
launchctl limit maxfiles 10240 10240
ulimit -n 10240
pdfunite *.pdf book.pdf