Thank you for taking him in!
I agree with Linette, 2 week old bunnies aren’t postcard-cute yet, so Ollie was probably a bit older. That he takes hay and pellets now is just great!
How does his “lethagic spells” manifest themselves? When a bunny is resting in perfect contentment it may look very dead. It can be very very scary even when you’ve seen it several times. Young animals ( I’ve only had puppies and a ferret) can fall asleep when they’re playing, sometimes mid-jump and be limp like rag-dolls. It’s natural. Young animals sleep a lot, it’s vital for their development and growth.
I also second Linette with the cuddling and touch and physical closeness. Bunnie-babies sleep close togeather in the warren when they’re young. All mammals need tactile stimulation to ensure normal development and general thriving.
Best of luck with your little one and please come back here with any questions you may have. It seems you’re doing great so far. Lucky little Ollie!