This is a common misunderstanding, encouraged by Wi-Fi marketing people. Mesh technology has nothing to do with how devices roam. Mesh determines how APs interconnect, not STAs.In my understanding, the Mesh term is about how the nodes operate in this network, including the roaming. Which is quite different from having multiple routers.
The primary things affecting roaming are the design of the STA driver and whether APs and STAs support roaming standards 11k,v and to a lesser extent, r.