Now that you have prepared your base 'soil' medium for sprouting your dragonfruit seeds, you need to 'plant' them in the medium, get them some water and let them sprout to become the dragonfruit seedlings from which you will cull weak seedlings then of the remaining dragonfruit seedlings which are the heartiest you will plant them individually to create the individual dragonfruit cactus plants to bring to full maturity.
You want to plant your dragonfruit seeds in quantity, and you are going to let them all sprout to become dragonfruit seedlings before you separate them (harvest the dragonfruit seedlings) for 'ex vitro' planting, so you do not want to plant them individually. You want quantity as your goal at this stage of the dragonfruit growing process. Use a tray or large surface area and shallow dish rather than a 'pot' for sowing your dragonfruit seeds.
Add to the dragonfruit growing tray a couple of inches of the dragonfruit growing soil mix (tezontle/soil, perlite/soil base mix) and then add a very shallow layer of just tezontle or perlite on top of this base soil layer. You want the seeds to rest in this fast draining layer of tezontle/perlite and send their first roots down into the soil mix you prepared earlier (remember the soil mix is the source of nutrients for the dragonfruit seedlings once they sprout roots, so the roots will reach into the base mix while the seeds are on top kept 'dry' in the fast draining pure perlite/tezontle layer. The layer of perlite/tezontle need only be 1 cm thick, just enough to keep the dragonfruit seeds off of the base soil mixture.