The picture of the Varde sink on the Ikea web site might be a little misleading. I think it has a skirt on it as shown in the cabinet installation.
IKEA | Kitchen cabinets & appliances | Free-standing kitchens | VÃ„RDE | Sink cabinet/ sink w double-bowl
I would verify this in person before proceeding.
If it is only available in a skirted version, that makes it trickier to install in an existing cabinet, unless that cabinet is of similar dimension to the Varde base and is freestanding. To install into an existing run of cabinets with an existing countertop might mean elevating the sink above the countertop (assuming it is structurally sound to do this - I don't know), or cutting through the countertop and maybe even into cabinet sides to mount flush.
Anyone who has actually examined this more closely, feel free to correct me if I'm wrong.