Sure, but this wasn't what the person you originally responded to suggested, they just asked if it would be possible to use the dynamic wallpaper feature with some that you add yourself (at least from what I understood).
I agree with that... it will mostly come down to whether or not Apple opens up that functionality. If they do, then we'd have access to a basically unlimited amount of dynamic wallpapers, seeing how there are plenty of time lapse videos and whatnot of all kinds of different locations on the web – picking out 12 different photos of such a time lapse or photo series wouldn't be too difficult.
If Apple doesn't open it up the dynamic wallpaper feature to those that you add yourself, or at least add a few more Apple-made ones than just a single one, then I view this feature as a proof of concept more than anything else because you'd have zero choice about it. You either like to use this very one wallpaper all the time, or you have other wallpapers, locations or motives that you prefer over the Mojave desert one and are completely locked out from taking advantage of the dynamic wallpaper feature.
Right now it looks like what we get is closer to the second of the two... but there are still a couple months till release, so there#s still some chance that Apple will add or change anything about it. It wouldn't be the first time that Apple added some more new wallpapers in one of the later betas; in fact they have done that a number of times over the last couple years.