If you have more than one Raspberry Pi or Debian/Ubuntu, install auto-apt-proxy on every machine, which auto finds and connects to installed apt-cacher-ng server. If you reinstall or download packages on multiple hosts this will save you bandwidth and speed up installations.

GUI to download Debian/Ubuntu - this must be the easiest way to install! No need to download full or minimal netinst iso images, no need to run md5/sha sum checks. Only the first install is slower, following installs will be lightning if using apt-cacher-ng

Define locale/packages in admin/config.php autoinstall with preseed.cnf soon

Can Live boot Debian and Ubuntu via NFS, can boot windows 10 setup

/etc/di-netboot-assistant/di-sources.list could be updated with more architectures like http://deb.debian.org/debian/dists/testing/main/ 

What would happen if Raspberry Pi4 was pxe booted? (I don't have one yet) http://deb.debian.org/debian/dists/testing/main/installer-armhf/current/images/device-tree/