More research is being done nowadays on various terpenes for pain relief. Unfortunately, because it’s strongly associated the cannabis industry, it’s hard to get past all the noise to the good information like research papers.
Most of the terpenes in cannabis strains are also found in other plants to varying degrees. Pure extracts are available and legal without question.
I can’t say much about their efficacy though, because I haven’t done a deep dive. Id love to hear from anyone who has done the research or has personal experience, especially without THC or CBD along for the ride.