No, yaySIM does not provide an unlimited data eSIM for Iceland. All of the plans listed for Iceland have a hard data cap, with the largest offering 100GB for 180 days and several 50GB options for 30 or 180 days.
Travelers who need a large amount of data can choose one of these fixed data plans. For example, the 100GB plan is valid for 180 days, and the 50GB plans are available for 30 days or 180 days, with the 180‑day version supporting 5G. Fixed data plans can be more cost‑effective for most users unless they are extremely heavy data consumers.