DYS, could open any child safe cabinet, or door protector. We installed, at the top of the door, a slide lock, to keep him inside. I once found him, standing on a kitchen chair trying to reach said lock.
The carseat we had him in had split arms on it, and they locked him into the carseat. I used a clipping chest attatchment, backwards so he couldn't get out of it. I had to make sure all belts and harnesses were on tight, or he could manipulate his little spider fingers around things to unlock them. The grocery cart belts he could open and close at 9 months.
We lived on the second floor of a 2 family house, and in the summer, I would leave the door open for air flow. I gated the stairs. He climbed over the gate, and fell down the stairs. I raised the gate up a few inches off the floor, he pushed the gate out from the bottom and fell down the stairs again. Finally, I put a rubbermaid tote under the gate, pushed down on the gate to make it tight on the tote and locked it in place. He was too short to climb on top of the tote.
He did all that before he could walk. He was also on a crib mattress on the floor, because he kept climbing out of his crib, before he could walk. I think if I would have had him first, there would not have been any more. He was my third, and some days made me seriously wonder why I wanted kids.