I live on a farm in rural Western Australia, and my wife and I have spent considerable time and resources in planting wind-breaks, shelter-belts and doing our local roadside rehabilitation.
As you would know, it's hard work to plant, and hard work to keep the seedlings alive for long enough to establish and grow.
That said, we visited a farmer in the wheat-belt once who was planting shelter-belts of tagasaste (tree lucern). They used a machine that ripped a furrow (common farm machinery), and something rigged behind it that would drop a seedling every x metres. The furrow would naturally funnel water to the seedlings roots.
Don't have any particulars on what the machinary was, especially the back part of it, but I'm sure tree farm companies (those that grow Pine, Bluegums, etc as a resource to later be turned into furniture, building materials, or woodchips) have some tools and techniques. Perhaps seek some out and interview or arrange for a tour.
Of course, all of those machines require fossil-fuels to get on site, to function, and to leave the site again. You win some, you lose some.
Even planting one tree, and allowing to survive, and grow is impactful. Trees are habitat to birds, insects, small reptiles, and some mammals. They are shade. They bring nutrients up from deep in the earth and make them available to smaller plants at the surface, enriching the ground. They are water-pumps, keeping the ground salinity low, and making that water available for rainfall further in-land of coastal areas.
Every single tree you put in allows populations of animals to live and flourish. You are making a difference. You're doing an exceptional job.
I digress a little, but even so-called "Weed trees" have habitat value. I have seen people cut down Willows and Sydney Wattles in our neighborhood, which are introduced and not wanted, and feel they have done a good job and are saving the planet etc. etc. But then they don't plant anything to replace them, displacing animals who don't have really anywhere else to go.