If it’s a zip down side why don’t you zip it 3/4 of the way down and tuck it in to stop the chance of rolling out? 🙂 as long as it’s clean and you have a new mattress I would say it’s probably fine (when you say grubby if there was any mould from being stored it needs to go. Cleaning it off isn’t enough!)
I have purchased my next to me crib from silver cross , mine has a bar that you can unclip and then you pull two zips down to let the side down, as long as you have it secured so it won’t come down it should be fine x
I've got a snuzpod 3 too. The side looks secure enough to meet the safety standards on mine as long as it is kept up while we sleep.
I was gifted a Snuzpod 3 also, didn't realise there was an element that didn't meet safety standards..I'll have to look more into it and make a final decision. If it is just the side down element I may just ensure I zip it back up each time that way removes the risk.