Ah the good old days of Sapper :'), the changes to the filesystem based routing to +page.ts +page.svelte +page.server.ts was really annoying to figure out initially, and +hooks as well, where to use what, what's the best way to do protected routes, took some re-learning, but it is what it is, would take the plunge to avoid React xd
I love Svelte but I've found myself disappointed by SvelteKit. Yeah it helps with rendering Svelte in the server and client but that's it.
And there are many weird architectural decisions forced on you such as file-based routing which IMO are a deal breaker for anything but trivial projects. Even as a SSG, SvelteKit still lacks fundamental features such as easy to configure permalinks at the page level (which Jekyll had almost 15 years ago).
I've started experimenting with integrating Svelte with Fastify using Vite to get a good backend framework instead of using SvelteKit. It's still a bit ugly but it works:
