As long as CPU hardware is closed source, perfect privacy does not exist, full stop. Conspiracy theories are futile, the probability of microcode backdoor is 1. So there is no need to "worry" about hardware blobs. There is NO way that processors made by US chip manufacturers do NOT contain a backdoor. The same goes for Raspberry Pi which is based on a Broadcom chip.
Privacy is a therefore probabilistic entity. Instead of worrying about hardware blobs, you should is try to estimate the cost of intrusion, collection and analysis, divided by the probability of yourself being a target. This yields a weighted cost of spying on you. If the result is high enough, no problem, as the adversary's budget s always limited. Otherwise you are toast, Tor or no Tor, VM or no VM. What Tor hopefully does is raise the cost and thus minimize the probability of the Tor user being targeted, collected and analyzed, due to purely budgetary reasons.
I am happily using hardware based on Intel chips. If I were an ISIS ringleader, I wouldn't. Allahu Akbar but my ass is valuable, too.