The Brief: "Cute NGL," shorthand for "cute, not gonna lie" is a way to compliment someone for being cute.

DEEP DIVE
The coy phrase “cute NGL” is a popular way for Gen Z-ers to compliment a friend’s appearance, to swoon over a celebrity, or to caption a selfie. Similar to “felt cute, might delete later,” cute NGL is a way of highlighting the cuteness of a person, animal, or cartoon character, perhaps one with smol bean-like characteristics.
You kinda cute ngl๐
— ยฐVtsoยฐ ๐๐ (@VtsoQT) January 3, 2020
Movie sonic plush?!
He kinda cute ngl pic.twitter.com/COzoxO4RKD— Crt (@strawhatcrt) December 21, 2019