I do wonder what his end game is though?...
He is going after Hancock most, because Hancock wanted him (hung) sacked for the Barnard Castle incident, then had that dreadfully confused and messy press conference of supposedly supporting Cummings "within the guidelines" while clearly not buying it himself "understand why nobody else thinks that". Also Hancock had a key role with vaccines, so must be really smacked down over PPE if he's to be ousted from any future leadership campaign. He isn't criticising Rishi Sunak, so he clearly thinks Rishi is very popular with the party members, MPs and/or the public.
Option 1: He's very very angry about being sacked and simply wants to hurt as much as possible everyone who was involved or who didn't help him.
Option 2: He hopes to get another adviser role. Cummings will see his only hope as working for someone who is a Remainer to give them a Brexit veneer. Javid and Raab don't need Brexit veneer. Hancock would stand, hence the need for smackdown. Hunt will stand again, possible. Clark also possible. Rishi likes to be seen as careful, it's impossible to imagine him bringing in Mr Toxic, but he may not go for PM next time (only 41, he has time) and will have a big voice so must be kept onside.
Option 3: This is prep for a book, in which the hero says everyone is a fuckwit except him and makes up a load of crap that can't be proven either way. It'll be called something like Cummings and Goings On at Number 10.