Knack debuted at 322,083 units sold in its first week via Famitsu. (Thanks to bundling with the PS4)
Knack 2 did not even chart in the top 30 of Famitsu with the lowest charting game on that list selling only 2,601 units.
References: https://sites.google.com/site/gamedatalibrary/game-search
https://s.famitsu.com/biz/ranking/
Edit:
Although Dengeki is a different tracker. They got Knack 2 at 2,106 units sold.
http://dengekionline.com/elem/000/001/605/1605038/
Knack 2 did not even chart in the top 30 of Famitsu with the lowest charting game on that list selling only 2,601 units.
References: https://sites.google.com/site/gamedatalibrary/game-search
https://s.famitsu.com/biz/ranking/
Edit:
Although Dengeki is a different tracker. They got Knack 2 at 2,106 units sold.
http://dengekionline.com/elem/000/001/605/1605038/