In a hot summer climate like yours, all day sun may be too extreme. Really prefers partial shade.

IME, perennial violas are not very long lived under the best of circumstances. A couple of seasons at best, even in my cool summer and mild winter climate.

Some perennial Viola can be long lived, and some can handle full sun, but the Pansy/Johnny-jump-up types of Viola don't do well in full sun and high temperatures. I wish vendors were more honest and realistic about their plants. The pansy type Violas are usually grown during the winter months in the southern U.S., and treated as annuals. I would maybe try one plant of the [("Celestial Moon")] 🙄 and see how poorly it does before investing more money on them. I get a kick out of some of these cultivar names, but obviously they do trigger a crave reaction to many and it makes people buy them. Namedroppers😂