Sorry, but no San Pedro in your photos. The photo on the left is a Myrtillocactus geometrizans in front, with Organ Pipe (Stenocereus thurberi) in the background. The photo on the right is Neocardenasia herzogiana. The white fuzzy ones are probably Espostoa. cd

Yes, you can cut sections - probably 4-6' sections would be easiest to prop / reroot. Cut with a hygenic knife / saw, set the sections aside to callous for a few days. Once the ends are dry, prop them up in pots with the cut end just into a thinnish layer of soil (and this soil should be porous). Heavily mist / fine spray the cuttings planted end every few days. If you can place the cuttings' pots on warm cement so much the better - the cut end will root faster. Repot / plant into the ground when the cuttings are rooted (should be in about 2 months, if that).

Did they germinate and then damp off? Or did they just never germinate? Place a thermometer in the dome if you are using a heat pad without a thermostat, just to be sure it doesn't get too hot. Sometimes under lights it can get pretty hot inside even without a heat pad. I think most cacti like to have it at about 70 degrees for best germination. .

Fill a pot about 3/4 full with commercial or homemade cacti/succulent soil. Press it down with your fingers or a spoon. Then sift some soil and spread it over the top, leaving a gap of 1/2 to 3/4” between the top of the soil and the top of the pot. Then put the pot in a pan with water and soak it, until the water has reached the top of the soil. Then take it out of the pan and let it sit for about 15 mins. Water will drip out the bottom, but that’s okay. Then spread your seeds evenly across the soil in the pot, and cover them with a thin layer of sifted soil or sand. It’s okay if not all of the seeds end up completely covered, but 50% or more should be completely covered. Moisten the soil with a spray bottle. Then cover the pot in clear plastic like saran wrap, and put it in a location where it will get indirect light. You need to be careful to get the right temperature, remembering that the plastic covering will increase the temperature the same way that the inside of a vehicle heats up when it sits in the sun and the windows are rolled up. In my experience 80 degrees is a good temp for these seeds. If you don’t have a thermometer feel the soil and compare to the temperature of your forehead. It should be a little cooler than your own body temperature. You should start to see sprouts within 7 days. I’m basing these instructions on my experience growing Bolivian Torch Cactus, which are in the same genus and very similar, and also contain mescaline. Incidentally, if you bought these seeds on Amazon, there’s a good chance they won’t grow, especially if they came from China. My suggestion would be to do this 7 seeds at a time, in 3 different plantings. The reason being that you’re likely to mess up in one planting. This way you have 3 chances to get it right.