Firstly, is there any reason you’re booking this as an IB codeshare? Booking directly with VY is usually much cheaper.

From my experience, VY are usually quite strict—not so much about dimensions, but definitely when it comes to cabin bag vs. personal item. Including yellow tags at the gate to prove to cabin crew that your bag can go in the overheads.

In a recent AA-ticketed itinerary, they randomly swapped my cabin bag for a checked bag with VY, and I was told I’d have to pay extra for a full-size cabin bag. (In the end, I booked certain seats that entitled me to an extra cabin bag.)

Edit: Forgot to add, VY isn't part of oneworld, so the text about cabin + personal doesn't apply, and VY rules will.