Aww! Lovley reading this! I’m so happy that Pip is really starting to trust you and you are forming a strong bond! Also, I happy to hear that you are adding improvements to his life with the Wodent wheel and bin cage! Such cute photos too!
The Kaytee Critter bath looks to big for a Syrian to bathe in. Do you have any plastic containers (like for storing a sand which in)? You can put the bathing sand in there so he has some more space to dig. You can just leave the Critter Bath in the cage as a hideout.