Can you monitor the frequency 433.215MHz via GnuRadio a standard RTL SDR DVB USB device?

Yes you should be able to, or with slightly more friendly software like gQRX or SDRSharp. It also looks like you can receive and decode the key signals using rtl_433[0] with option -R 64. Although it's a bit confusing looking at the source for the honda key rtl_433 decoder, as the author states it does not decrypt the rolling code.[1] According to the CVE there is no rolling code.

[0] https://github.com/merbanan/rtl_433

[1] https://github.com/merbanan/rtl_433/blob/master/src/devices/...