That's one reason why Launch HNs usually include a demo video. That's the link you should be clicking on if you want to see these guys' product. If you do that, you'll see that it isn't vaporware.
We also advise startups doing Launch HNs to provide a link for users to try the product (preferably without a signup gate, but that's not always doable). There's such a link in the text above as well.
I suppose one way to avoid complaints about stub websites would be not to link to them at all—but then other comments would say "why would I trust you, you don't even have a website"!
Edit: I've replaced https://runsift.com/ with https://app.trysift.dev/docs in the text above. Perhaps that will help.