The question you linked to is indeed identical, but the answers assume who-knows-what conditions are present under Fedora, and those assumptions do not fix the issue. Maybe that's a better place to ask the question, though.
- systemd-networkd is, in fact, the default in Debian 9, yes? Then why is my .link file being ignored? udevadm info does list the link file, but it seems that other names override it.
- An answer to the above-linked question suggested placing a .rules file in /etc/udev/rules.d, which I have tried and that did not work. This is no surprise, since /usr/share/doc/udev/NEWS.Debian.gz specifically tells you not to do that anymore.
After more reading, I noticed that /usr/share/doc/udev/NEWS.Debian.gz points you to /usr/share/doc/udev/README.Debian.gz, which has a mention of doing a
After rebooting, my interface is now renamed correctly. Hope that helps for anyone else looking to rename their interfaces.