I would like to import shapes into Libre Draw
You could import (as an extension) openclipart. Probably LibreOffice slows down then, but it’s worth a try.
And there are some other extensions for LibreOffice (search for gallery) and or OpenOffice (search for gallery). The blue men is from OpenOffice extensions.
found an excellent source of Network shapes from VRT Network Equipment Gallery
https://extensions.libreoffice.org/en/extensions/show/vrt-network-equipment
Mark Lautman provides a lot of shapes on Custom OO Shapes. License: Creative Commons Attribution License (CC BY)