Steel, then yes, as it can be welded or brazed relatively easily.
Don't expect to get much though.

Also interested in this since I have a cracked Croix de Fer frame sat in my garage and it seems a shame to throw away something that is 99% fine (it's a fairly crucial 1% that's cracked, though!).

Where does one sell these things? eBay?

The only bike a ever regret selling was an EBB Inbred with a bent chainstay. It was at least usable, and got £80 for it.
It yours is not even usable, then it will be a very limited market, but could be the basis for a home fabrication cargo bike or tandem.

Yes! I found it really hard to find any semi decent steel frame to use as a donor for a cargo bike. Anything chromoly or better is worth selling. Tons and tons of old Ally frames were fairly cheap but steel bikes either don't exist anymore or become 'retro' and crazy expensive

Thanks for the responses - I'll put it on eBay and see if there's any interest. Would rather that it goes to a good home than being melted down...

I had my snapped Airdrop Edit up for sale on Pinkbike for ages then ended up giving it to a mate who welded it up and rode it for a year before snapping it again

Anyone want a full suss frame? No damage and really solid frame unlikely to snap 😀