If we’re talking about legal ways only (no hacks or tricks) — to get a grey government tick on Twitter (X) you need to apply the same way as for the gold one. They’ll ask for documents proving the account really belongs to a government body or official. On top of that, Twitter usually checks if there are articles or mentions online confirming that this person or organization actually exists and is connected to the authority they claim.
So it’s not something you can just buy — it requires official proof and public recognition.