I agree on Blackout, but I always feel the need to note it anyway.
Agent Carter is very much a prequel to Agents of S.H.I.E.L.D., though. Dark Force/Zero Matter, the Faustus Method, the Hydra theme from Agents of S.H.I.E.L.D., Daniel Sousa in Agents of S.H.I.E.L.D., Nitramene in Agents of S.H.I.E.L.D. and Agents of S.H.I.E.L.D. using the Agent Carter theme from the One-Shot in S2 in their Peggy Carter flashbacks.
Point is, if Agent Carter is canon, it would be ridiculous if Agents of S.H.I.E.L.D. wasn't. I mean, an entire character is devoted to explaining the Hydra brainwashing in present day.
Agent Carter, just like Agents of S.H.I.E.L.D., is off the Marvel Cinematic Universe section on Disney+, so it's not like they internally regard it as more. Since we know the former is canon, the later probably is, too.
Kevin Feige has confirmed it's canon itself. When asked about Blade in the MCU, he pointed out how Agents of S.H.I.E.L.D. used the character, and how, while there were no plans at the time, he has the potential to appear in any of the shows.
WHiH Newsfront referenced Agents of S.H.I.E.L.D. S3.
Essentially, it's all certainly canon, and we can very likely never worry otherwise after Spider-Man: Homecoming 3.