you dont need that much power to do “pentesting”…, i had a Dell latitude laptop with 16gb ram and thought it was too much and switched to a basic 4gb laptop with i5 3320M for 50 euros. i run gnome desktop on it using archlinux and it does not get paste 1gb of ram usage and my cpu around 5 % each threads, i also get 4 hours of battery on wifi with firefox open. thats the advantage when installing everything yourself, you choose what you need and nothing else.
my advice : gpu is useless, you wont crack much and you can always find something else to do it instead of you (if you catch what im saying), ram is useless even if you use VM, 8gb should be the maximum (now if you want to play Fortnite while doing HTB machines, thats your own problem). any processor will do as long its at least ivy bridge, go for intel processor if possible, really.
the most important factors for me is portability, resilience, and battery life, which is why i choose between 10 et 12.5 inches laptop that are of strong material.
when saying you need 8gb ram at most for VM, i assume you use VM in cli mode using 256mb of ram for each