Over on his YouTube channel CWNE88 has posted how he has been using and RTL-SDR with the rtl_433 software to explore the data coming in from various 433 MHz ISM band devices in his neighborhood. In the video he explains how he has set up rtl_433 on his Raspberry Pi, and what sort of data he is receiving. Some examples of devices he's received include various weather stations, doorbells, remotes and car tyre pressure monitors.
He also mentions how these signals are unencrypted, noting that in a future video he will show on GNU Radio how a false signal could be synthesized.
Decoding 433 MHz Devices With SDR