Just posting this in case anyone else makes the same mistake.
I'd been having problems with my install of LE and decided to wipe it and set up a new one. I'm using kszaq's 8.2.2.3 release and decided to stick with it as I'd got everything working on it. Everything went fine until I tried to get the VFD working again, as installing the driver stubbornly kept producing
Open device failed.
: No such file or directoryerrors despite using the vfd.conf file that had worked before. After getting frustrated for a few hours I found The Coolest's post on page 7 and decided to try downloading the dtb's attached, even though I thought I had the right one already (ethernet and wifi were working fine).
Switched the dtb and Boom, the vfd works. I must have managed to download one without the generic entry that's needed.
Many thanks to The Coolest for his work here.