Yes. You can, but only if you have a mild case of vaginal dryness.
Although sea buckthorn oil pills and NeuEve suppositories both deliver nutrients to the tissue. The former is systemic delivery; the latter is topical delivery.
When you take sea buckthorn oil pills orally, it is systemic delivery. The nutrients like omega-7 and vitamins are absorbed in the gut and transported through the blood circulation to all over the body. It will help you achieve an overall, systemic relief of dryness. These include dry eyes, dry mouth, skin dryness and vaginal dryness. After absorption from the gut, the nutrients are spread to all over the body and are diluted by the body fluid. Each particular body side only receives a small amount of the nutrients. Thus, its effect is relatively weak for each body site.
On the other hand, the NeuEve suppository delivers all of its nutrients including sea buckthorn oil topically to one body site - the vaginal tissue. It is not diluted by the body fluid. Since the nutrients are not diluted and all are delivered to a single site, it is more effective for relieving tissue atrophy in this site. However, the trade-off is that topical delivery of nutrients to one site cannot relieve dryness in other body sites like dry eyes, dry mouth and skin dryness.
If you have mild vaginal dryness and painful sex, and also have dry eyes, dry mouth and/or skin dryness, taking the sea buckthorn oil pill alone may work well for you.
If you have moderate vaginal dryness and painful sex, but you do not have dry eyes, dry mouth and/skin dryness, vaginal application of NeuEve suppositories alone may work for you.
But if you have severe vaginal dryness and painful sex, regardless if you have dry eyes, dry mouth, and/or dry skin, a combination of both oral ingestion of sea buckthorn pills and vaginal application of NeuEve suppositories works better. The reason is that an atrophied tissue may recover more rapidly if it can receive nutrients from both directions - inside from blood supply and surface from the topical delivery.