Strictly following canon laws of Project Hail Mary (book or movie) the chances of Grace and Rocky meeting characters from Star Trek is pretty much 0.
However - strictly following canon laws of Star Trek (movies, books, tv shows, etc) the chances of THEM encountering Grace and Rocky is far from zero. In fact: Meeting them would hardly be the strangest thing they have ever done. It wouldn't even make the top 100.
(Dude... they had an episode where two characters got evolved/devolved into amphibian-lizard-things due to going to warp 10 threshold and then subsequently made lizard-amphibian-babies on an alien planet! Then got turned back to normal. No they didn't take the babies with them. So! Them meeting Grace and Rocky is not a stretch!)
Crossover media? Check. (Doctor Who in Comics).
Modern Times? Check. (Every show has some time-travel shenanigans).
Historical figures? Check. (To many to count).
Alternate Universe shenanigans? Check. (Again... too many to count)
Historical figures that are outside our timeline? Check. (Tons!)
SO -
It's paradoxically plausible for Grace and Rocky to encounter and interact with Star Trek characters from any era.
You're welcome. :)
(Lol I just want to see more PHM/Star Trek crossovers of any variety.)