The post comes before the advert, and it names the owner
A job advert is written by a company. A hiring post is written by a person, and it is nearly always the person with the problem: the head of the team, the founder, the director whose headcount was approved that week. They post because it is free and quick, and because they hope their network will save them the advert.
That gives you two things a job board cannot. The first is timing: the post often appears before the role reaches a board, and sometimes the role never reaches one. The second is the name. On a job ad you have to work out who owns the hire. On a post, the author has told you.
The catch is volume. "We are hiring" is one of the most common phrases on LinkedIn, and much of it is written by recruiters advertising their clients' roles. The play is mostly a filter: search narrowly, remove the agencies, keep your discipline, qualify the company, and only then pay for an email address.
What you get back
A table of the posts that survived: the author, their title and confirmed employer, the link to the post, when it was posted, a short summary of the role, and whether the company fits your desk. For the authors who pass, a verified work email and a drafted opener. In-house talent posts sit in their own section: evidence of demand, seldom the right first contact.
If you asked for staging, the people are in your paused campaign with their openers attached. Nothing has been sent.
Variations worth knowing
Narrow by the author's title. The search can be limited to authors whose headline contains a title you name, such as a finance director. It is the cheapest way to lose the recruiters.
Read what else they have posted. A person's recent posts can be pulled as a separate, charged read. It tells you whether this is one role or a team being built.
Check the boards as well. Find every company hiring in your market covers the advertised side. A company that shows up in both is further along than either signal suggests.
Where this goes wrong
Broad keywords. A single common word matches everything and every page is charged. Use the phrase a manager in your market would write, and add the role.
The author is not always the owner. Colleagues share openings for their team, and founders post for every function. The confirmed title tells you which, and the opener should fit the person you are writing to.
Public posts only. Posts limited to someone's connections, and hiring that happens in private groups, are not visible. This is a view of demand, not all of it.
Everyone else saw it too. A popular post draws a crowd of suppliers quickly. A relevant opener sent the same week is what separates you, and build an outreach sequence covers what follows it.