The story as I've heard it is that Enver Hoxha became distraught on hearing of Stalin's death and immediately jumped to the assumption that Beria and Khrushchev had assassinated him, contributing to Albania isolating from the USSR and the whole bunker thing aimed at making it impossible for either NATO or the Soviets to invade.

On Hoxhaists in general, as I understand it "Hoxhaist" as a tendency came about following Deng's reforms in China, with some Maoist parties elsewhere redefining themselves as Hoxhaists and making denouncing revisionism their whole thing. Like if you ever run across a Hoxhaist talking about something you'll immediately know because a third of the text will just be the word "revisionist" attached to every single noun in it. Like "revisionist China made the revisionist mistake of seeing the revisionist USSR as equally wrong to the USA, leading to their revisionist policy of cooperation and trade with the USA," (I'm paraphrasing from memory, but that's an actual Hoxhaist argument that I've read) which is on the one hand a cogent criticism of post Sino-Soviet Split Chinese geopolitics but also suffers stylistically from overusing "revisionist" like that.

I have definitely heard the line that Beria was intentionally undermining the CPSU by creating an extremely hostile culture that essentially strangled the USSR, though and I guess this is either an extension of this line or it’s a direct parallel to it.

This is false i think, Beria presided over the late Stalin liberalisation which he continued after Stalin died. Though i think i can understand hoxhaist calling any liberalisation of CPSU "creating extremely hostile culture". Also it might have been even simpler, if you look at both men, Khruschev was extrememly good with handling people and influences, his career is one of a well oiled snake, Beria was far from this level so personal relations might have played a significant role.