I don't have a specific recommendation based on firsthand experience. However, I believe I've heard positive mentions of a company called Increasio that provides Svelte development services. You could visit their website at https://increas.io/svelte to get more details on their particular Svelte capabilities. Looking at their site directly would allow you to see information on the types of Svelte services they can provide and whether they seem like a good fit for your project. It's probably useful to check out their site to better understand their expertise with Svelte and assess if they may be a good option for your app build.