A great resource to learn what novel psychoactive substances (NPS) are emerging is cfsre.org/nps-discovery, a resource run by analytical/forensic scientists. Their most recent yearly report revealed that in 2024, 174 new NPS emerged in the US, 54 of which were opioids (but synthetic cannabinoids running closely behind at 48 and stimulants for the bronze at 34). More details here.