[dbrgn]

You can do something like this:

    export interface OpaqueTag<UID> {
        readonly __TAG__: UID;
    }
    export type WeakOpaque<T, UID> = T & OpaqueTag<UID>;

And then use it like this to create a newtype:

    export type PublicKey = WeakOpaque<Uint8Array, {readonly PublicKey: unique symbol}>;

To create this newtype, you need to use unsafe casting (`as PublicKey`), but you can use a PublicKey directly in APIs where a Uint8Array is needed (thus "weak opaque").