Labor intensive activity. make sure that ground under trees is bare so nuts can be easily found and picked up. Get LONG cane fishing poles, wait until nuts are ready to fall....very late fall....climb into trees, go out on big limbs, thrash the outer limbs bringing nuts to ground, pick up nuts from ground.
Mechanized equipment very expensive, includes an arm attached to a tractor that closes around limbs and pulls/pushes to vibrate limbs and make nuts fall, then a pickup device with rubber fingers pulled behind a vehicle that picks up the nuts.
50+ years ago, there were people who would come out and do the thrashing and pickup nuts on shares. Entire family affair, typically with lots of kids to clamber out on limbs to do the thrashing and pick up the nuts. Times have changed, I haven't seen anyone in Texas doing it on shares in many years.
Do it yourself, or put an ad in Craig's List for people to come do it on shares.....insurance liability is large from falls, etc....for small return.