Suwari Gata: the first step in learning these sitting forms is understanding the kamae of fudoza. For our Japanese counterparts in the art who culturally grew up sitting in seiza and fudoza as me might sit cross legged style or in a chair, many of us westerners are not used to sitting like that. There is a difference in sitting and being able to do a waza, and sitting comfortable and doing a waza.
If you can’t sit seiza or fudoza with the same relaxed manner you might sit in a chair then you will miss the transmission of the waza and the movement feeling it is trying to teach.
These should not be thought of as “ground fighting” (ne-waza) but rather as ways of using a solid surface- in this case the ground, but it could also be a wall, to support your movement.