Yes. 20719 supports mesh.
Currently 20819,20719,20706,20735 chips support ble mesh.
ModusToolbox IDE(MTB) is the latest IDE.WICED Studio is old one. CYBT-213043-02 mesh module (mesh kit) is included in MTB.
Current version of MTB does not support CYW20735 chip and few modules.
Is the MESH function program easy to develop?
Absolutely. It is easy. I would suggest you to go through below lab manual and app note.
- CypressAcademy_WBT101_Files/Labmanual at master · cypresssemiconductorco/CypressAcademy_WBT101_Files · GitHub (chapter7)
- Video lecture: How To Design With Bluetooth Mesh (Hands-On)