D.B.
For in the house... use the high chair. You can make pudding or jello and let him "fingerpaint". You can put blocks or other toys on the tray to play with.
He'll be strapped in and safe in the high chair while being up high enough to see everything around him too.
Ditto the thought about a carrier. Although the backpack types he might be long enough to push on the frame with his feet. That might be nixed if you buy shoes with laces and just tie the shoes together?? or buy little sandals that you can tie together with a shoelace to keep him from using his feet while in the carrier, if its seems to be a problem.
Best of luck!
D.