You can use a list view instead of the data grid and put the dynamic class on the Status attribute (with currentObject) of this list view?
Unfortunately the default “Dynamic classes” option does not work on the attributes of the row for columns..
We use the Cell Styler widget to add custom classes to our columns/rows . Nowadays it even supports nanaflows which makes it very easy to use.
Prefer using list view and then give conditional visibility to the attribute value of status. You can use 2 display values of attribute value. For pending visibility set its color as desired and similarly for completed.