Spruce is absolutely fine
It's better than pine. There is an article somewhere that shows that although softwoods have high levels of phenols, that Spruce is the exception and is equivalent to hardwood. Even solid pine is ok in large panels, rather than shavings. It is cedar I would be concerned about.
If you don't mind a suggestion - I think it would be better to leave the top shelf in but remove the bottom one and have deeper substrate so it comes just under the second shelf. The drawer at the bottom isn't much use for cleaning anyway as it's too shallow for substrate. Hammies need at least 3 to 4" and ideally 6" or more is good. You have an ideal cage for deeper substrate, which will add to the enrichment and cushion any jumps or falls. You can put any hard floor toys under the shelves.
The second shelf would be a good place for a wheel - or underneath the top shelf (with the bottom shelf missing) but it might need to stand on something if you have deeper substrate (eg a short platform or similar). Or you could have a nice big house under the top shelf on the substrate so your hamster can build a big cosy nest for winter.