I had a few minutes. This turns out to be really easy to do with FastAPI:

    from fastapi import FastAPI
    from starlette.responses import StreamingResponse
    from fastapi.middleware.gzip import GZipMiddleware
    
    app = FastAPI()
    
    app.add_middleware(GZipMiddleware, minimum_size=0, compresslevel=9)
    
    def lol_generator():
        while True:
            yield "LOL\n"
    
    @app.get("/")
    def stream_text():
        return StreamingResponse(lol_generator(), media_type="text/plain")

Away it goes, streaming GZIP compressed "LOL" to the receiver, and will continue for as long as they want it to. I guess either someone's hard disk is getting full, they OOM, or they are sensible and have timeouts set on their clients.

Probably needs some work to ensure only clients that accept GZIP get it.