Fresh grass clippings are similar in their makeup to food waste if we compare their carbon C, nitrogen (N) and phosphorus (Ph).
Food waste averages 49.5% C, 3.8% N, and 0.51% Ph.
Fresh grass is 44.9% C, 3.4% N, 0.2% Ph
These percentages are so similar, that as long as the grass is well distributed through the Subpod when added it should be fine.
Remember to add sufficient dry carbon as you would when adding food waste. The only downside of adding fresh grass to your system is if the lawn contains weed seeds, these will not be killed in the vermicompost process and would be present in the compost.