There are a number of statements like "QUIC is functionally equivalent to TCP+TLS+HTTP/2" in the "QUIC wire specification" and other documents, and this agrees with what I remember seeing in the source in the Chromium repo when I last looked.
I've not read about the IETF version; I'll look into it.
I haven't been following QUIC very closely, but from what I understand, they have put in a proper abstraction between the TCP+TLS part and the HTTP part. While the mapping of how to use HTTP over QUIC is still part of the spec, as I understand it, there shouldn't be any major problems mapping other protocols onto it.
I've not read about the IETF version; I'll look into it.