Firewall by David Mack

A thrilling prequel adventure based on the acclaimed TV series Star Trek: Picard!
Two years after the USS Voyager's return from the Delta Quadrant, Seven of Nine finds herself rejected for a position in Starfleet...and instead finds a new home with the interstellar rogue law enforcement corps known as the Fenris Rangers. The Rangers seem like an ideal fit for Seven-but to embrace this new destiny, she must leave behind all she's ever known, and risk losing the most important thing in her life: her friendship with Admiral Kathryn Janeway.