too many character...
You can sell local to people you know, unlikely get caught but make sure to tell friend to never write about it in any messaging app, never ever even to their friends. Only say face to face, and if stranger in gym walk up to them asking to buy, maybe police, don't tell anything or they can get arrested for illegal use and you for manufacture and sale if they get evidence... Your friend and his friend and his friend, they are idiot. Probably one will be stupid and get you caught one day, who know. I don't care I am bored maybe prison for few years is unique experience...
Online locally? very easy with anonymous letterboxes if can manage to get strangers to trust you, but this is very illegal so I don't recommend for inexperienced hobby criminals. Digital mistake in advertising, communication, payment, it make them find you instant... If not that then physical problems... Fingerprint... DNA... Cameras... Long term surveillance over boxes, one day you may even be caught while they look for another criminal by bad luck. One must think very outside box to lay low and not be too easy to catch. If you low priority you can get caught by being sloppy with routine. If you are high priority, they will probably get you eventually no matter how smart you are. Time is on their side. One time I saw police sitting in a car far away looking with binoculars. I don't think looking for me, but maybe...