Anyone will say congrats on the new place. The real ones show up with a dolly and carry the couch up four floors.

Congratulations cost nothing and are given freely, which is why they carry so little information. Turning up to do something physically unpleasant on a weekend is a different order of commitment, because it costs time and effort that cannot be faked. The gap between the two is where you find out who is actually around.

Keep a note of who appeared on the hard days rather than the celebratory ones. Then be that person: offer specific help on a specific day instead of saying to let you know. And if you needed help and did not ask, notice that too.