Can one actually get data out of that thing, without uploading it to some random company?

Live Data on APP: requires a GW1000 WIFI gateway(sold separately) to connect to WiFi, after the WIFI configuration,the live soil moisture data can be viewed on the WS View mobile application

Graph & History Records on Ecowitt Weather Server: supported to upload to our free Ecowitt Weather server(ecowitt.net) to view the soil moisture data graph and download the history records on the website; it's recommended to add a shortcut of the website on the home screen of your phone for quick access

EDIT: It seems you don't need the bridge if you use rtl_433: https://news.ycombinator.com/item?id=33286401