Java can do the same with a library like Gson or Jackson

Jackson is no where near as convenient as Go's marshaling system.

.NET has System.Text.Json.

I wonder how does it compare to go's implementation

.NET is ok, but the classes you make serializable generally aren't how you'd write a normal class, which is what I mean by "ergonomic." As far as I know, you need your fields to be public for both reads and writes, and you need to write a separate constructor if you want to create the types programmatically. Go lets you serialize objects more-or-less how you'd write them without serialization, as does Kotlin.

Record types introduced in C# 9 solves this.

It's now as simple as

record SomeData(string Name, int Id);

Which gives you an immutable object, auto generated constructor, and some additional helpers to make life easier.