Speer makes these little plastic bullets for .45 and .38/.357 which you can just handload into brass (and I mean literally load by hands without a press), and shoot with primer only. All you need is a hand priming tool and a deprimer (or virgin brass). They are not toys, and could potentially be deadly, at about 400 fps. But relatively safe and fun. I have been known to shoot these from a .45 down the hallway. You still need a fan going for ventilation due to the primers and some semblance of a backstop (2 or three layers of surplus carpet will do).
But between your options of:
1. Speer plastic bullets, rubber bullets, & wax bullets (primer only), and
2. Airguns, and
3. Airsoft, and
4. Aguila Colibris from a .22lr rifle
All of which require some degree of backstop, but nothing excessive, I think that the idea of shooting lead bullets around the house is a really bad idea. It also may be illegal (check your local laws).