So, we know that the official on Linux support is "not any time soon", and as a regular and somewhat competent Linux user I understand the reasons for that. (Suffice it to say that it would be considerably more complicated and labour-intensive to provide and support than you'd think.)

But it occurs to me that for a good chunk of the games catalogue, we're already halfway to Linux compatibility without any effort on GOG.com's part, because they're only playable on modern computers through what Ashens calls "the dark wizardry of emulation". They normally use DOSBox, which has been ported to Linux, Android and several other platforms that I bet very few people here have ever heard of.

To which end, is there any possibility that we could have a download option that consists only of the original DOS executable and other files, without the customised copy of DOSBox.exe or the installer? Some documentation on any custom settings needed would also be helpful.

Linux folks have asked for that in the past, and GOG pretty much put that possibility down right there. They weren't willing to provide those zip files for Linux, so I doubt they'll offer them for DOS.

But, the GOG version is pretty much always the DOS version when there is one.

Getting GOG.com DOS games to run on a MS-DOS Time-machine

Also, GOG's idea is (well, was, until they started adding new games) getting the classics to run on modern operating systems, DOS isn't one (admittedly, GNU/Linux, the *BSDs, and Solaris are, but apparently they don't count yet).

You're missing the point. What they are asking for is the same files that GoG currently distributes, minus DOSbox for windows and other bits and pieces not relevant to playing the game.

There's no chance in hell as things stand right now, but there you go, I've enlightened you. Hopefully.

I realise that, but the point was never simply to sell old games, but to sell them ready-to-run on modern (Windows) systems (OS X support and new games were added later), including a zip with the original files for use on DOS isn't relevant to that end.

Download the Windows installer and extract it with innoextract. You might need to tweak the DOSBox configuration files to suit your purposes since GOG puts the autoexec section in a separate file.

Note that a couple of GOG releases are native ports and don't have the DOS files at all (e.g. Raptor: Call of the Shadows 2010 Edition).