Many buck drivers are unsuitable for driving a single LED from 1s. This is especially true with LEDs which have a high Vf (forward voltage). When HKJ reviewed an older LD-29 I do not think that he found it impressive on 1s.
Some time ago lagman wrote an informative article to help beginners with some driver-related concepts. I eventually edited that to make it more boring. For now I’ll recommend that you read/skim that to get a better handle on things.
I can’t imagine going through the rest of your shopping list without including an LED swap!