I own a Raspberry Pi, a tiny ARM-based Linux computer capable of running many DOSBox and SCUMMVM games. I also own a large library of GOG games that are designed to use DOSBox and SCUMMVM. Unfortunately, the GOG Linux installers are not compatible with the Raspberry Pi, although the contained game files are.

Hence my question: Would it be legal or against the EULAs to make copies of game folders from my Windows GOG library for use on my Raspberry Pi?

You can also use innoextract to unpack GOG installers.
No need to install the game first.

I don't see the issue as long as you don't distribute said games (but then again I am not a lawyer) the only thing that could be against the law would be if you had to crack a DRM to do so (because of the DMCA) but given that the game is DRM free it's not even the case. Recent Gog installers are just renamed RAR files (the bin files) so you don't even need Innoextract.

Legal.

It's perfectly legal since it's always you who'll be using them. It's no different than Linux users running Windows games in Wine :-)

Yes. Probably yes, as EULAs are always so strict, prohibiting absolutely everything. If you believed in EULAs, you wouldn't even be able to fart in public.

Best comment on EULA's I have seen was on the EULA screen for the classic "Beavis and Butthead:Virtual Stupidity" adventure game: On top of the Eula scroll screen are the words, in huge letters; "LEGAL CRAP".

Btw, Virtual Stupidiy, if they can get the licencing issues fixed, should be on GOG. A really good game, one of the few games based on a TV show that really captures the flavor of the show..and has realy good gameplay in it's own right.

GOG stopped using RAR installers quite a while ago ;)

I would not worry about it. Stranger things have happened.

Ah ok, my bad, I wasn't aware of that :)

Here's the official response I received from GOG support, for anyone else who is curious:

My view is you can basically do whatever want with your games, besides piracy of course (no uploading to pirate sites, no handing out copies to friends, stuff like that.) Do what you want as long as it stays in "your own hands" or perhaps even immediate family's. My suggestion (probably obvious): contact Nightdive with this suggestion.

So how do I play Sid Meiers Pirates then?

nice one.

as for OP - only limit to amount of installed copies is related to machines, you dont own (e.g you cant share your swags with others, for free or charge). Aside from that - you can install your games everywere - on your pc, on your laptop, on your tablet, on your car, on your toaster, on your calculator, on your dog's tracker. For as long, as said devices can launch them, obviously.

Like really - GoG cant even count amount of devices, you installed games on (but games may include developer's/engine's own telemetry)