Regarding the specific grocers and delivery; Vons, Safeway, Albertsons, and many others are all owned by the same parent company. They are similar, but not identical. In most areas, Vons has their own delivery service. All the major grocery delivery services also support Vons including Instacart, Uber Eats, and Door Dash. All the major delivery services also support Sprouts, as well as other major grocers.
If you have an account with any of these delivery services, it will list what grocers are supported, and I expect the list of supported grocers will be far more than just the 2 nearest grocers you listed. For example, if I change my Instacart deliver address to near the Vons/Sprouts in Echo Park, it lists the following grocers all being in delivery range – Albertsons, Aldi, Blackjack Market, Bristol Farms, California Market, Costco, Costco Business Center, El Super, Food4Less, Fresco Community Market, Gelson’s, Grocery Outlet, Lazy Acres, Ralphs, Sam’s Club, Sprouts, Stater Bros, Super King, Superior Grocers, Target, Tokyo Central, Vons, Walmart, and ~20 others.
I also live in SoCal, in an area with a similar nearby grocer list. If you aren’t familiar, Sprouts is a specialty store that emphasizes natural, organic, and produce; often at higher prices than elsewhere. It does not have a markup above sticker price on Instacart. Vons does have a markup above sticker price on Instacart or other delivery services. However, Vons does not offer a markup on their store delivery service, which is likely to lead to a lower net price if you are purchasing without an Instacart x% off coupon or discounted gift cards.
Most grocery delivery services will give you a free trial to test them out and find which one(s) you prefer, often combined with a 30-50% your order type deal.