Does it mean it's not available for my specific version of openwrt?
If I have to compile it, then I guess I'm out of luck unless there is somewhere I could ask someone to do it for me?
rtl-sdr - 0.6.0-3 - rtl-sdr allows DVB-T dongles based on the Realtek RTL2832U to be used as an inexpensive SDR. This package contains the utilities and daemons.