"so the small corner tray I was expecting is actually the size of my head"
That really made me laugh! I get this one - it's just the right size for a Syrian
https://www.amazon.co.uk/Trixie-Corn...576994&sr=8-10
Yes he probably just needs a few nights to adjust to his new house and routine - he'll be fine in a week's time. Great that he's moved into the house!
This is the Exotic Nutrition Silent Runner upright wheel - how confusing that there is a flying saucer called a silent runner as well! I think if Exotic Nutrition find out they may sue them for using the name!
For an upright wheel it's one of the best but not cheap. Totally silent, spins really well, safe and sturdy and not bulky depthwise. I find they last much longer than other wheels as well and you can get a cage mounting attachment as well instead of the stand (I use that as I can then have the wheel higher up above the substrate).
https://sugarglidershop.co.uk/produc...nner-12-wheel/
The other silent upright wheel that's popular is much cheaper - and has a cork running surface - nice for their feet. It does need painting with plastikote really though - inside at least and on the running track - so it's wipe clean or they can get stinky. The 28cm size is the right size for a syrian.
https://www.zooplus.co.uk/shop/small..._wheels/609617
Cheapest option is the plastic trixie wheel which is very popular. Not silent but most people find it quiet.
https://www.amazon.co.uk/Trixie-6101...5577527&sr=8-1
If you have room in the cage he'd probably appreciate both an upright wheel and the flying saucer - but you probably haven't now the house is at floor level. Yes it is because the old wheel was too small that he wouldn't use it I bet - that is common - it can be uncomfortable for them if its too small and cause back pain.
Personally I would swap out the flying saucer for an upright wheel and keep the flying saucer for the playpen if no room in the cage, but he'll be fine for a while.