If foreign actors like Russia decide to influence the Fediverse (which is already highly radicalized), they’d have a very easy time.

If? Did you see the mental gymnastics and agitprop going on around the election to get Trump elected? One or more nation state botnets is already deeply entrenched here. Since the election they became inactive and the stream of murder/suicide-“leftist” posting died down. Denialism of the Russian disinfo operations, which are well documenteted at this point, is also decently common here. I will probably get a comment about it in fact.