As we know, NIST PQC project is at its 3rd round, with draft standard expected to arrive in the next (few) year(s).
An unfortunate fact is that, we’re not seeing many signature schemes general-purpose enough (in the sense that, the size of some of their cryptograms may be large). However, the lattice-based PKC/KEM algorithms have favorable cryptogram sizes.
In SSL/TLS, the forward secrecy feature is where the server signs an ephemeral key for use in key exchange, so that the compromize of the static key doesn’t expose past communications.
Currently, there is a draft on hybrid key exchange at IETF. My question being: is it possible to achieve forward secrecy by using 2 public PKC/KEM keys, 1 ephemeral and 1 in the certificate, so as to save bandwidth at the same time?