The Epic First Run programme allows developers of any size to claim 100% of revenue if they agree to make their game exclusive on the Epic Games Store for six months.
After the six months are up, the game will revert to the standard Epic Games Store revenue split of 88% for the developer and 12% for Epic Games.
I had a few games on Impulse but my account vanished when it got sold to Gamestop so I can understand people being worried about buying games on other platforms. One reason I like GoG due to offline installers