If you liked Project Hail Mary, then you should read the Bobiverse series by Dennis E. Taylor. The premise is as follows:

Bob is dead. Long live Bob.

Software engineer Robert Johansen uses his share of the money from the buyout of his company (the rest having been split amongst the employees) to start a trust to support his end-of-life maintenance needs. But Bob's idea of "end-of-life" is being cryogenically frozen until such a time as whatever killed him can be fixed. What he wasn't counting on, however, was getting hit by a car later that day and waking up over a hundred years later. Finding that, not only has he not been revived, but instead digitised, but also that the christofascist government doesn't recognise him as a human or worthy of rights, he is surprised to also be informed that the reason they instantiated his consciousness was to become the guiding intelligence of a Von Neumann Probe, and that Bob is going to the stars... At least, he should be, as long as none of the opposing factions in the government or any of the other countries also building their own probes nuke him first.

Bobiverse is an example of hard science fiction, with similar limitations to what PHM uses. The primary conceits that go beyond what's currently assumed to be possible are:

1. the assumption that it is possible to simulate consciousness using electronic media
2. the existence of some method of interacting with the fabric of reality to warp spacetime through a reactionless drive (here called "subspace theory"). This assumption allows for interstellar travel over reasonable time scales (but not superluminal travel) and, later, communications. Think a combination of the "Ansible" and the Bussard ramjet from "Tau Zero"
3. the fantasy that most people have comprehensible reasons for their actions.