In this section of the page, we will see evidence seen on the official Marvel pages that the 6 series are canon.
MCU Nick Fury Biography: The MCU Nick Fury biography mentions the events that occurred in the final episode of Agents Of S.H.I.E.L.D. Season 1, where Fury helps Agent Phil Coulson defeat John Garrett, a former protégé of Fury who had revealed himself to be The Clairvoyant.
LMDs: In an article titled "MCU Robot Roundup" on the official D23 Fan Club website, Cassandra Pinkney listed the various robots and androids seen in the MCU—including Vision, Ultron, and H.E.R.B.I.E. from The Fantastic Four: First Steps. Notably, the article also mentions Life Model Decoys (LMDs), which were introduced in Agents Of S.H.I.E.L.D. Season 4. This implies that Disney still considers the Agents Of S.H.I.E.L.D. series to be part of the Marvel Cinematic Universe.
James D'Arcy's Previous Appearances In The MCU: A press release document for the VisionQuest series, found on The Walt Disney Studios website, details that actor James D'Arcy's first appearance in the MCU was in the Agent Carter series, where he played Edwin Jarvis, Howard Stark's butler. This indicates that Disney still considers the series—produced and broadcast by ABC—to be canon and part of the Marvel Cinematic Universe.