In the US, advertising a medical device legally amounts to marketing it, and marketing a medical device that is not exempt from pre-marketing approval or acceptance of a pre-market notification is illegal.
So, the only legally permitted advertising for an uncleared (i.e. not just submitted-510[k], approved 510[k]) medical device in the US is minimal announcements at international-attendee-attracting trade shows where the device will be shown, stating that it may not be sold to US buyers.
Such "not for sale in US" cards are very common at the annual RSNA show, for instance.