I know one of the biggest DDF readers told me that you most have a minyan AP halacha when making a bris
R’ Zimmerman of Lakewood who performs a ton of brissim has done plenty without a minyan in the last couple of months. My brother is be”h making a bris next week with 3 people. They have a minyan for Shacharis anyway but the mohel said he will not perform a bris with a minyan, so the bris will be at 12, way after Shacharis.