By their own admission (or at least those of their advocates who I've paid attention to) tRPC isn't suitable for large projects.

tRPC as I understand it basically serves definition files to the client using a clever misuse of Typescript - but over time that means Typescript has to conditionally evaluate every type in your app to find the correct one. Or something like that.

My understanding of BlitzRPC from their documentation is it's more Svelte-like with the "everything is a magic compiler" philosophy. This may come with issues but it sounds pretty nice.