The next table shows you for each level what internet kitten collectibles you unlock (so you can then find those ones too) and also the level up reward that a second and future sims will receive when they level up in this hobby:
The next table shows you for each level what internet kitten collectibles you unlock (so you can then find those ones too) and also the level up reward that a second and future sims will receive when they level up in this hobby: