It doesn't feel like Legion has release waves like X-Wing but I noticed that the game designers talk in waves during live streams about products. I'm wondering if anyone is in the know of Legion waves. Does anyone know how FFG determines and classifies waves for Legion? I'd like to know what they are talking about because they say it like we all understand what they mean.

The development cycle will be similiar to their other products like X-Wing and Armada, which have waves and are also done by the same team of designers. It's only for Legion that the sales team decided to spread the releases. I think we can only estimate what the 'Legion waves' are but looking at other products I think there is a good estimate:

Wave 0: GCW Coreset

Wave 1: Rebel Troopers, AT-RT, Airspeeder, Stormtrooper, Speederbikes, AT-ST

Wave 2: Fleet Trooper, Leia, Snowtrooper, Veers

Wave 3: Rebel Commandos, Han Solo, FD Turret, Scout Trooper, Boba Fett, E-Web

Wave 4: Wookiee Warriors, Chewbacca, Imperial Royal Guard, Palpatine

Wave 5: Rebel Specialists, Pathfinder, Jyn Erso, Imperial Specialists, Death Trooper, Krennic

Wave 6: X-34 Landspeeder, Sabine, Occupier Tank, Bossk

Wave 7: Rebel Veterans, Tauntauns, Shoretrooper, Dewback

Wave 8: Clone Wars Coreset, Clone Trooper, BARC Speeder, B1 Battledroids, Droidekas

But who knows? Maybe Wave 7 and 8 should be combined into one.

Makes sense that they are talking about dev waves and not necessarily releases