Once we get our own mods, I would encourage them to be proactive, even annoying about telling other mods our scope and quality requirements. In the early days of SR, I would ping a moderator from another site and tell them not just that what they migrated was off topic (unclear, not enough requirements, whatever), but also why. Pretty soon, we had people across the network that knew what we accepted and didn't. That's helped a lot.
Also, on SR, I go through a list of comments on Stack Overflow that link people to SR without a link to our quality guidelines. I then ping them with this comment:
@[type here] Software Recommendations moderator here. We have fairly strict quality guidelines, so I'd appreciated it if you would link to our question quality guidelinesquestion quality guidelines whenever you recommend someone re-ask a question on the site. Thanks!
To which I've only received positive responses. I'm trying to fight back the ocean here on Stack Overflow, but this site is lucky: Stack Overflow doesn't get that many hardware recommendation questions. We don't have as big a battle to fight.
I'd encourage our moderators, when we get them, to adapt that comment to this site and fight the same battle. I'd also ask our users to do the same if they'd like - we have a chance to seriously reduce the number of bad "but they told me to come here" questions we get.