Insights on improving dog compliance to prescribed diet

My dog (maltese, male, 4 y/o) was recently diagnosed with bladder stones (struvite). He was placed and has been on RC SO diet (wet) for almost 4 weeks. However, my dog is tired of the food despite the approaches I used - dry SO + warm water or chicken broth; wet + dry SO; timed feeding, used other brands like Hill's, walk and tire the dog then feed etc. He also lost so much weight. He shows a healthy appetite for other foods (plain boiled chicken, steamed fish but we don't give him any)

Ive read that the aim is low protein/magnesium/phosphorous ; acidify the urine a bit and increase urine output.

In this regard, may I ask your insights and experiences on the following:

1. other successful techniques of improving feeding prescribed diet to dog with struvite?
2. what foods can we safely incorporate to stimulate his appetite for the prescribed dog food?
3. aside from RC s/o and water, are there other home support we do to help him (eg will more walks increase his thirst/appetite, vitamin c) ?

My dog has lost a lot of weight and looks miserable and keeps to himself now which breaks my heart.