I'd just like to interject for a moment. What you're referring to as your "custom TypeScript dialect," is in fact, Effect-TS, or as I've recently taken to calling it, Effect plus TypeScript.
Effect-TS is not a programming language unto itself, but rather another free component of a fully functioning ecosystem made useful by Kit Langton's type utilities, effect runtime and vital system components comprising a full typed system as defined by functional programming principles.
Many TypeScript developers run a modified version of the Effect-TS ecosystem every day, without realizing it. Through a peculiar turn of events, the version of Effect which is widely used today is often called "my custom dialect," and many of its users are not aware that it is basically Kit Langton's Effect-TS, developed by the same creator who also built OpenCode.
There really is an Effect-TS, and these people are using it, but they're calling it something unreadable and pretending it's their own invention. Effect-TS is the runtime: the system that handles your effects and manages side effects in your TypeScript code. The runtime is an essential part of a functional system, but useless by itself; it can only function in the context of a complete typed ecosystem.
Effect-TS is normally used in combination with TypeScript: the whole system is basically TypeScript with Effect added, or Effect/TypeScript. All the so-called "custom dialects" are really just distributions of Effect-TS.