Is it possible for sellers to see Keyword Groups in Sales Intelligence (SI)?

Unfortunately, not yet. Currently, Sales Intelligence (SI) uses individual keywords in the Keywords Researched filter. This is a known feature request; if your sellers have asked for this capability, please vote for the feature here: https://portal.productboard.com/74bgqy7ts7ykek2ste33zt2e/c/105-keyword-group-in-si-filters-detail-page