I live on Oahu and use Instacart frequently because I hate dealing with parking at my Costco. One thing to know is that the online prices are generally 20% higher than you'll find in stores. There is also also a delivery fee and a tip is customary. All in all, expect to pay 30%-40% more than you would in store. If you order alcohol, your delivery person will need to imput your ID information into their smart phone so make sure you have that available. The upside is that they almost always deliver on time and nothing is missing from the order. The delivery person will text you if something is out of stock (which is rare) and ask if you'd like a replacement.
I think Safeway usually offers a $20 off $75 coupon for home delivery services.
Shipt is Target's delivery service. The advantage of Shipt is that there is no markup. For groceries, the Target's online prices are almost always cheaper than in store. For example, the brand of canned tomatoes I buy is $1.39 online but $1.99 in store. If you place a large enough grocery order, you may end up paying less for delivery than you would in stores, even after accounting for delivery fees and tap. The downside to Shipt is that deliveries are often late. On average, I'd say 10%-20% of the items I purchase online are out of stock and only more expensive replacements are available.