While it is best when growing dragonfruit from seed to grow the dragonfruit seedlings, repot the small dragonfruit seedlings and let them grow individually to small dragonfruit cactus plants, and then plant at the final location of the dragonfruit cactus plant, you can try to skip the intermediate step of transplanting the dragonfruit seedlings to individual pots to get them to large enough size for final planting.
Direct planting of dragon fruit seedlings from the seed tray: If you want to skip the intermediate step and plant the dragonfruit seedlings where you want the mature dragonfruit cactus to grow outdoors (if in a greenhouse, then skipping the intermediate step is less risky), make sure when you sow your dragonfruit seeds initially that you use:
1. Much deeper base layer of dragonfruit soil mix (soil/perlite/tezontle)
2. Much sparser distribution of the dragonfruit seeds (at least a few inches)
3. Much more time to grow the dragonfruit seedlings to larger dragonfruit cactus
The idea is that you are going to sprout the dragonfruit seed and let the dragonfruit seedling just keep on growing until it is large enough for the final transplantation, so you need to have plenty of space for the dragonfruit cactus to put down roots and to grow larger in the original tray.
Of course, you could plant each dragonfruit seed individually in its own pot...
Planting dragon fruit seeds in individual pots: If you elect to skip the seedling repotting step altogether by planting one seed in each pot, most likely the result you will find is that by trying to save time and energy, you are actually spending more time and energy! You'll end up with a lot more space taken up and a lot of wasted work because any of the dragonfruit seeds that don't form vigorous dragonfruit seedlings are not ones that you want to propagate. If you sprout all the dragonfruit seeds first by the recommended method, you can easily pick out any that are sub-par at almost no loss to you other than the seed itself. If you try these shortcuts, any dragonfruit seedling that isn't viable enough to keep represents a huge amount more wasted work and you will be tempted to save it anyway! Not a good idea.
If you are lucky and virtually every dragonfruit seed gives a robust and healthy seedling, then by all means - it may be easier to plant each seed separately. It's a gamble.
Direct planting of dragon fruit stem cuttings / dragon fruit vine cuttings: A not unreasonable way to go if your dragon fruit growing conditions are good and you are propagating your dragon fruit cactus plants from stem cuttings, is to plant the cured stem cuttings directly in their final location outdoors. It is again taking a greater risk, as the dragon fruit plant will likely have more stress than if you potted it and let it get a good established roots system before transplanting it outdoors - it is a gamble worth testing out, as if your growing conditions and the climate dragonfruit grows in are ideal for you, you may have good success.