Black Panther may have been ambiguous regarding its more fantastical elements, Moon Knight has been anything but, especially in the latest episode, "Asylum."

It was always left to chance that the vision brought on by the consumption of the heart-shaped herb caused one to hallucinate Wakanda's afterlife 

but the latest episode of Moon Knight no longer leaves any doubt about it. The Ancestral Plane is real, which carries significant implications for the rest of the Marvel Cinematic Universe moving forward.

In Episode 5 of Moon Knight, Oscar Isaac's Marc Spector begins to question if they're in "the" afterlife, but Taweret corrects him,  

saying that it's merely "an" afterlife. The goddess names the Ancestral Plane as one example, which she finds "gorgeous."

This confirms that the Ancestral Plane seen in Black Panther wasn't a hallucination brought on by the heart-shaped herb, but an actual heaven-like plane of existence Wakandians go to after death.  

Something which would explain the appearance of N'Jadaka's father, N'Jobu, in the Ancestral Plane, despite having never consumed the herb. 

As Thor and the rest of the Asgardians are highly advanced and powerful aliens in the MCU, it's uncertain if Valhalla exists as an afterlife, if it's merely another dimension, or simply part of Asgardian myth.