Released in 1997, DOOM 64 was developed and published by Midway Games and was considered the pinnacle of the series at the time, despite being a spin-off. Decades later, it was ported to PS4 in 2020 by Nightdive Studios and included as a pre-order bonus for DOOM Eternal. According to an updated ESRB listing, it now looks like it's coming natively to PS5.
The listing, spotted by GameRant, suggests that a reveal may be imminent. Submitting a title to the ESRB is one of the final tasks necessary to ship a game, and developers need to ensure that the associated label on the box is as accurate as possible. We can't imagine what major improvements it would feature, as the PS4 version, running on PS5, is already capable of a locked 60fps at 2160p; we suppose we shall just have to wait and see.