I'm not sure we've quite gotten to the bottom yet on Bloomburrow singles, but in most cases, it'll be better to buy singles you need now as compared to when cards first came out
For example, graded Alpha Black Lotus copies have sold for tens or even hundreds of thousands of dollars, with price guide values in the same range
Regular Creatures, Sorceries, Enchantments, and more can only be played during their owners turn, but Instants can be cast whenever their owner chooses
While the green one is far and away the most versatile and easy to find a use for, none of them are unplayable, and all can slot into your mana bases without much trouble, especially given they enter untapped
Since Nadu can keep putting lands onto the battlefield, you can keep triggering all your landfall effects to make an army of tokens