Hackberry just needs sealing on the ends, you can even go ahead and debark it without sealing the back. I have a stash just like that that never checked at all on the back even after bark removal. If you cut it down to stave dimensions though, it may start warping and twisting on you, so maybe just halfsies for a bit, then quarter up after it's dried a bit. Course you could go on and rough it out and clamp it to a form while green i hear and it'll dry in a few weeks. Hackberry's a pleasure to work, and smells wonderful when heated
Can't wait to try smoking some meat with some of my scrap pieces!
Hackberry can be difficult to split, but if it's straight you can do as Randman suggested and cut down the length with a circle saw. Get it as deep as you can imo, mine only went about 1.5" and the other side sure didn't wanna come apart as easily as i split it!
Do give it a pesticide treatment and keep indoors if possible. Bugs find it easy to work too
Good luck with whatever you do with it!