It wasn't just potatoes, or any food, it was many things, that if something wasn't exactly right there would be a huge disengagement to whatever was going on at the time, sulking, no accepting of an apology for upsetting them, no matter how innocent the mistake. It was exhausting. So yes I think that particular trait of sulking and being moody after an innocent mistake from someone who then apologises for effectively nothing but even that's still not enough, is more than likely a ND indication.
And yes they had very specific interests that were all from online or gaming, because they didn't really leave the house, which you listened to, but try telling them something about you and there was no interest. So back to listening about some unique Youtube creator. I can understand why some would find that obsession quirky, fascinating, passionate, but for me it was exhausting.
Someone else said upthread, if it's always you making the adjustments to try and not end up upsetting someone or walking on eggshells then you might guess that person has some ND. At a guess.
The teens have other friends with various ND diagnosis many hang out here a lot. And there are NTs who sulk. But with some the sulking and power games is beyond anything reasonable.
The original ones haven't been here since, it was too difficult, for us. And perhaps some will see that as a failing by us, but all relationships are give and take and this was just give give give and it still wasn't enough for "pick a reason". And again that might be a sign of ND sometimes. And yes they might have felt extremely uncomfortable here, just as they were making us all uncomfortable in our home, so it's not like it's hard feelings or anything just have to accept that sometimes friendships don't and never could work out.