Can I use webflux for my client to receive real-time notifications?

Question

I have two systems, 1 legacy and the new system. The new system will need to be updated in real time, every time the legacy is updated. With that I thought webflux would help me, so I created a POC with Mongo and such,

@RestController
public class ConversionTableProductTypeResource {

    @Autowired
    private ConversionTableProductTypeService service;

    @GetMapping()
    public Flux<ConversionTableProductType> getAll() {
        return service.findAll();
    }

    @GetMapping(value = "/stream",  produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public Flux<ConversionTableProductType> getAllStream() {
        return service.findAll();
    }

    @PostMapping()
    public Mono<ConversionTableProductType> createTweets(@Valid @RequestBody ConversionTableProductType tweet) {
        return service.save(tweet);
    }

    @DeleteMapping("/{id}")
    public Mono<ResponseEntity<Void>> deleteTweet(@PathVariable(value = "id") String tweetId) {

        return service.findById(tweetId)
                .flatMap(existingTweet ->
                        service.delete(existingTweet)
                                .then(Mono.just(new ResponseEntity<Void>(HttpStatus.OK)))
                )
                .defaultIfEmpty(new ResponseEntity<>(HttpStatus.NOT_FOUND));
    }

}

And then I thought this was the solution to my problems, because I thought, the legacy could update Android and my screen would magically update.

It may be that my tests were not correct, because I called the /stream by browser or by Postman.

Could shed some light if I’m thinking the right way, and if so, what I did wrong?