Agree with Cypher - a lot of things supposed to be suitable actually aren't. Bendy bridges are one of the most popular toys - they can be a ladder, or a tunnel or a bridge and come in different sizes. I have these two:
This medium one is quite large - it makes a good tunnel - at the moment I have it on its side and used as a fence to separate different areas of substrate
Medium Bendy Sticks Flexible Wooden Bridge Hamster Mouse Gerbil Toy 4008: Amazon.co.uk: Pet Supplies
This one is a good size for a Syrian - I have one over Charlie's house entrance door so it makes a tunnel entrance, but also a ramp/bridge to climb on top of his house.
Kerbl Willow Bridge, 130 x 210 mm, Small: Amazon.co.uk: Pet Supplies
I think you already have a sputnik - which is a great toy. My other favourites are these
The 10cm medium boredom breaker tubes - ours is hung from the roof next to the sputnik - with sisal string, but they can also be good for the floor of the cage or partly submerged under substrate. They are stronger than toilet roll tubes so the 10cm size is best for a Syrian (ie if it's too small they can't chew out of it so easily).
Boredom Breaker Rat Medium Tube: Amazon.co.uk: Pet Supplies
I think these little hay cottages are good toys too. It's a cardboard house with hay stuck on the outside (stuck on with vegetable products) and dried carrot or coconut on top. Ours rarely gets used as a house but makes a good step/level, an extra hide - something to climb onto out of his other sputnik, and you can put them on their side instead to make a kind of hide area.
Rosewood Naturals Carrot Cottage Hamster House, Small: Amazon.co.uk: Pet Supplies
Our favourite proper toy is this hanging kabob thingy. The wooden blocks slide up so you can hide little biscuits or treats in them. I changed the bottom ring on ours and swapped it for a standard keyring ring, which is much larger (I was worried about a foot getting caught in the small ring).
https://www.viovet.co.uk/Small_N_Fur...+n+bob&sct_r=1