I lent 'Love & Gelato' to my cousin, and she loved it so much she immediately bought 'Love & Olives', thinking it was the next one. She was so confused when Addie wasn't the main character! She had to go back and get 'Love & Luck'. So from a practical, avoid-confusion standpoint, tell your friends the right order. It saves them a headache. The titles don't make the relationships obvious.
Can we talk about the covers for a sec? The redesigns for the paperback editions are gorgeous and clearly meant to be seen as a set. When you line them up in publication order, the spines create a lovely gradient or a cohesive visual. That's a silent nudge from the publisher about the intended order.
It's a cosmetic detail, but book design often reinforces reading order. In this case, the visual series order is the publication order.
It's book #1. The series isn't a continuous narrative, so the 'order' is mostly about publication sequence and catching Easter eggs. For instance, in 'Love and Luck', the main character mentions following a blog about Italy—that's a nod to Lina's blog from the first book. Tiny things like that make reading in order a slightly more connected experience.
The audiobook is fantastic for a 'reread'. It feels different enough to be a new experience, especially with the Italian pronunciations and ambient sounds.
Finally, a practical point: if you're buying them as gifts, know your recipient's age. A 16-year-old might love 'Gelato' and 'Luck'. A 22-year-old might prefer 'Olive Oil' and 'Chaos'. The timeline progression inherently categorizes the books by the protagonist's age, which is a great guide for matching book to reader. It's a series that gracefully handholds you from YA to Adult fiction. You can start at the beginning and grow with it, or you can jump in at the point that matches your current phase of life. That's clever publishing.