3D Realms came up with an FAQ about their upcoming RTS not too long ago and provided some rather interesting universe lore.
The latter has already enjoyed some well-deserved success and as such, it is not really out of the blue that 3D Realms would place another game they are working on in the same universe. After all, if the players are already familiar with it, they are more likely to get invested in the lore and the characters' or factions' motivations.
In fact, one of the factions in Tempest Rising is literally the same one that appears in Ion Fury.
Global Defence Force (GDF) is the organisation that Shelly, the Ion Fury protagonist, has ties to and occasionally works with. In Tempest Rising, GDF are one of the two main factions you get to play with.
One of the two available campaigns has them as the protagonists, with the opposing side being the Tempest Dynasty. While assuming a security organisation could be the "good guys" is not without merit, the devs stated there are no good guys in Tempest Rising as they were not going for a black-and-white depiction of characters.
Tempest Rising is a prequel in a way, with the story events taking place about 100 years before Ion Fury as things that unfold will lead to the rise of Dr. Jadus Heskel, who Bombshell players are probably familiar with.