Kyrope made this super cool picture of Desert Glass uncorrupted and said she's a terraformer like Lapis Lazulis. (I'll totally buy it.)
Also here's what'd happen if she was freed: after they heal her (but I'm sure she could've been freed and healed in "Change Your Mind") she'd become emotionally attached to her pillow and even fix it when it broke (cuz when Lapis was freed the mirror she was in broke) and she'd keep it. She'd also hate Jasper after learning about what she did to Lapis and would date Lapis and treat her better than Jasper did.
Also, here's another theory: Desert Glass is actually a Lapis Lazuli whose hole was filled with sand while she was incubating (which would explain her resemblance to a Lapis Lazuli) so she was seen as "defective" and became a Crystal Gem; however, she was corrupted trying to hide Larimar from the light (and both of 'em were corrupted).