At this point in time, you can't selectively upload photos to the cloud. I don't know if Adobe plans to add this in the future or not.
Thanks for the reply.
That renders their cloud features completely useless. I have >500gb of photos. I don't want or need them all uploaded, and with the current setup I can't send _anything_ between devices...
If you have a lot of images, you should use Lightroom Classic. Lightroom Classic can selectively sync. It only syncs smart previews but that is usually more than good enough to edit on mobile.