We're going to add pre-moderation in the future - https://github.com/unaio/una/issues/2321
However most probably it will not happen anytime soon.
One possible solution for now to enable pre-moderation in Market is to set status to non-active by default by executing the following query:
ALTER TABLE `bx_market_products` CHANGE `status_admin` `status_admin` ENUM('active','hidden') NOT NULL DEFAULT 'hidden';
So by default market products will have hidden status, this status can be changed by admin/moderator only, so this could be some sort of pre-moderation.