I think it’s totally normal to be nervous, especially when your own sister has been the one to have it, there will be a niggling worry there about your parents as well.
Personally, I have been fine with visitors and the baby. It’s only family we’ve had to the house and we see them several times a week (and they helped me with the older kids after my section) any friends I’ve met elsewhere, or one or two in the house actually now I think of it, but they haven’t held the baby. Not because of covid, just because I don’t usually hand my babies over that easily