Alliance Unbound is the sequel to Alliance Rising, which won the Prometheus Award for Best Novel in 2020. It appears that this may be the second volume of a trilogy, as the final pages leave important issues unresolved.
Taken together, these novels form a prequel to Cherryh’s Alliance/Union series, one of the larger future histories in the past few decades. (It began in 1981 with Downbelow Station, which won her first Hugo Award for best novel.)
The crucial fact driving its events is scarcity.
There are only three planets with biospheres: Earth, Pell’s World, and Cyteen. Orbital habitats in other solar systems — notably Alpha Station, located at Barnard’s Star, where Alliance Rising was set — are ultimately dependent for supplies, especially biomass, on those three systems; Alliance Rising’s plot turned on Earth’s starving Alpha Station of resources to advance its own goals, and a key point in Alliance Unbound is the discovery of nearly priceless Earth goods on Downbelow Station, which orbits Pell’s World.
Cherryh and Fancher’s characters are well aware of such issues of scarcity and value, being interstellar merchants who spend their lives going from solar system to solar system, with holds full of high-value cargo and computer memories full of equally valuable data.
