well, I have an update. So I take Gavin on a stroller walk Tue/Thur/Sat. He knows my routine, and I was getting ready and went to the back to get my shoes. I hear Gavin moving around, by the time I can run into the living room, he was standing! he somehow got himself up, so he got a nice hug and I helped him stand a bit before I helped him back down. On his walk, I got him out and laid him on the grass for a break. He wasn't having it and wanted to get up. I helped him up and he walked/stumbled a bit.
I just got him home, and he was just trying to get up again from his dog bed. So back into his crate. I really don't want him straining too much too soon. I will keep up with 3 potty breaks in his wheelchair a day and some assisted stands to help build things up. But it's a good sign. I think I will have to crate him more often though, as before he couldn't even really try and get up so he just laid in his beds whereas now he is definitely trying.