Starfield credstiks appear to be Starfield’s version of the bottlecap stash from Bethesda’s Fallout series, or gold pouch from Elder Scrolls titles. Collecting credstiks will reward the player with a random amount of credits, however the range of the rewarded credits has not yet been revealed.
As this particular item is consumed on pickup, it likely does not have a mass, unlike other consumable items.
Starfield credstick trivia:
The Starfield Constellation Edition comes with a copy of the Starfield base game stored on a Credstik-themed USB stick.