Thanks to @dohyunkim for reminding me to be thorough!

At least in our own files. A patch has been sent upstream to apply the
same change to the generic loader.

It’s sort of official now ;)

The “AFM” code stays since PFB accompanied by an AFM file is still
supported by the fontloader.

Unsupported as of now. They were only ever supported by accident and
very incompletely, which was misleading.

The Lua fontloader doesn’t support these formats and they’re very low
priority. There is no “shortcut” like with the FF loader anymore which
would parse such files into the same data structures as {O,T}TF. Support
for postscript formats may come back at some point in the future if
there is demand.

Another take on https://github.com/lualatex/luaotfload/issues/334

The parsing issues we aim to prevent occur with spaces because Luatex
treats them as argument separators. Hence apply quoting only if
necessary. Also use the appropriate format string as a defense against
garbage inputs.