E-commerce is a recently developed platform on Freshdesk which would enable you to bring the Ebay channel into the helpdesk. This is a feature enabled upon request and so kindly contact us on support@freshdesk.com in order to bring this as an option on the admin tab.
Once this is enabled, you could see this in Admin -> Channels -> E-commerce where you can add a new account. This new account would need your eBay site information and you would be able to assign product, group and such.
If you signed up before Aug 9, 2021, please click Previous plans to view your applicable plans.