Does this product exist?

Sort of. All current combo units with an ATSC tuner, like the panasonic EZ48, can tune in HD channels, but they output and record in SD. From a practical standpoint, the output still looks very good (DVD quality), but isn't HD. If you must have an HD tuner perhaps because your HDTV lacks one, you'll have to get a seperate box. IIRC, the 48 will record digital channels (HD and SD) only to DVD, not VHS. If you plan to use it as an HD tuner for an analog tv, it should do fine.

I've been using a couple of Panny EZ48s with an OTA antenna I got for $10 at Big Lots. I have another connected to my cable through which I get (for some odd reason) the HD feed for my local channels.

The OTA picture is better than what I get through the cable.