it is less obvious whether two drunk people who think they’re giving consent can (morally/ legally) give consent.

It isn't. Neither of them can consent, full stop.

Whether it is rape however gets determined in court by a judge and potentially jury. Burden of proof is on the accuser etc etc.

If neither of them charge the either with rape, then neither of them have raped the other.

From a legal standpoint

If you don't have a rape conviction on your record, you are not a rapist... from a legal standpoint. Full stop.

The question was "can they consent to have sex with each other", which is technical inherently. Consent is a technical legal term.

Now, what many people perhaps are instead in this thread addressing is the question: "Is it ethical to have drunk sex with someone who is trying to consent"

And I would say yes, its fine, under the following conditions:

Condition 1: You have had consensual sex with this person before under sober circumstances

If there is already a pretense for consensual sex with this person and this is a followup to that, then it's much more reasonable to assume that they want to fuck again. If this is the first time sex is being initiated however, I would politely decline but let them know that if later, when they are sober, they still wanna fuck, then I am game. I have a personal rule that my first time I have sex with someone should be when stone cold sober... Not just for consent reasons (which is obvious as a reason), but I want the first time we have sex to be when I am at my best performance and able to make a good first impression.

Condition 2: There was already prior implied consent before they got drunk

If this person was hitting on me and indicating an interest in sex before they started drinking, and now that they have had a drink or two they are following up on that prior consent, that's also fine imo. If someone is chatting me up and flirting, indicating they are into me, and clearly signaling intent while sober... then they go get a bit tipsy and come back and indicate now they REALLY wanna fuck... that's also fine because it's clear even when sober prior they were interested.

In other words, if I have never had sex with them before and there was no indication when they were sober they wanted to have sex, and only once drunk suddenly now they wanna fuck... thats a big nope from me, I steer clear of that situation and politely decline as thats not going to be really consensual, and even from an ethical standpoint I can't bring myself to have sex with someone who only demonstrated interest once drunk.