Oh love, it's not easy. And you're right, the people with singleton babies won't get it (in the same way, as others have said, that people who haven't experienced it don't get the difficulties of having a child with SEN, or several children close in age, or single-parenthood). But the problem here is that their kindly-meant advice just doesn't work. And because of Covid, nor does the 'standard' twins advice of 'take help when it's offered/get out and about even if it's hard' etc.
It will get easier. And you will get through it. It is really, really hard. You're doing your best. And they will be carried around and cuddled less than single babies - they have a different experience, just as an oldest child's experience is different from the youngest. It's OK.
My twins are 12 now. The first year of their life was really, really hard work. We'd had an incredibly difficult lead-up to it with a family death, a high-risk pregnancy and relocating to the other end of the country. But we got through it, and it got easier, and having them is truly a blessing and a joy (though not without its challenges and difficulties, of course). You will get there.
Some stuff I found helpful that still applies in Covid times:
Prioritise sleep where you can (I know!!). In our case, that meant DH sleeping in the guest room twice a week, and me doing so once at the weekend (he'd wake me up to feed the babies, but I just did that and then went back to sleep).
Look after each other. We were both prepared to suck up bursts of really hard work for the other one's benefit.
Drop your expectations where you can - e.g. housework, nice cooking. It's fine, you can do it all further down the line.
Changing station upstairs and downstairs. I had a toothbrush downstairs too. Somewhere they can nap downstairs (moses basket if tiny, or buggy, or just a little 'nest' on the floor. They can wear babygros, don't need to faff around with clothes.
Good luck with it. You'll get there.