So Confused...upgrading from Cubase AI 10.5

Hello,

So confusing…I want to do this right. i am interested in upgrading from Cubase AI 10.5 that I received with my Yamaha keyboard…and want to get to Cubase Artist 10 or 11. Steinberg shop for upgrading appears to only show going from Cubase AI to Cubase Artist 11. https://new.steinberg.net/cubase/

Two questions:

Is Cubase AI 10.5 the same as Cubase AI?
I have seen upgrades online from Cubase AI to Cubase Artist 10.5 (e.g. musicians friend)…are these still a legit option?

Thank you for any help!

If you mean for the upgrade path on the Steinberg site: Yes

Depends on the seller. If they sell legit versions, it is legit to buy them.