The two searches, and where the box shows up
Somebody asking why their driveway is cracking gets an explanation, often in a box above the results. Somebody typing driveway sealing and their town gets a map and a list of companies, because Google can tell they want to hire, not to read.
That's the split worth holding onto. The box is common on the first kind and much less common on the second, and the second is the one that ends in a phone call.
What changed
The box names the pages it built the answer from, and people click those. So an explanation search that used to send you nothing can now put your page, with your name on it, in front of somebody two steps before they're ready to hire.
Google has also started showing businesses inside the answer, with a way to call from there. That's the map pack in a new suit, fed by the same things: your listing, your reviews, and pages that say you do that work in that town.
How much work it sends today
Not much, honestly. Visits arriving from assistants are a small share of what a contractor site gets, and anybody telling you a big number about that is quoting something nobody measured.
Where it matters is influence. People ask an assistant who does this kind of work near them, get two or three names, and then search those names. You don't see that as a visit. You see it as somebody calling who already knows who you are.
So the thing to watch isn't a traffic number. It's whether you get named at all, which you check by asking the question yourself, in each engine, once a month.
What this changes about what you build
Nothing, which is the useful part. The page that gets you on the list in a town is the page an answer engine quotes for that town, because both are looking for the same thing: plain sentences about one job in one place, with the facts in one spot.
There's no separate AI product to buy. Anything sold as one is selling you the pages you needed anyway, at a markup for the word. If a proposal has an AI line on it, ask what physically gets written that wouldn't have been written otherwise.