I think "need to interface with" is a bit of a stretch though. If we
need to interact, it's probably a business interaction, in which case it's probably going to be via email or phone, and even if SMS is required it's going to be simple messages. Social protocol in these situations means we're unlikely to need the features like sending high-quality images or video, or reactions/stickers, etc... So we'll happily interact in a professional way, no problem at all.
However, if we're sitting around playing super mario at a mutual friend's place, and the iPhone user says something like "Oh, I'd invite you to the group chat, but you're an _android_ user, so uncool." yeah, we don't need to interface in any way, and likely won't ever be friends in any substantial way. You've just signaled you're fundamentally not a nice person, and that's all the information I need to decide if I want to spend any further time around you. There are many such other signals, some widely accepted by society and some simple personal preference. (For example if we're in the same situation and you're a heavy social drinker who just wants to go to bars I'm similarly unlikely to invest time in you as I don't drink personally.)
"talking about you behind your back" likely goes both ways. In my friend group we mercilessly mock people hanging off of Apple's every announcement and panic-buying a new phone as soon as the store comes online just because it has a feature that our android phones have had for 9 years now. I think this is just an in-group social thing that happens everywhere. Some people judge others by the sneakers they wear. The problem comes in when you lump everyone into this "other" category and treat them as lesser. I'll make fun of a iPhone user for their lack of awareness of the reality distortion field they live in, but I'll still be friends with them. (My best friend is getting the new phone that was just announced.)
Mocking someone behind their back because they don't make the same choices you do is just a fundamental signal that you're not very open minded and probably not the type of person I want to spend time with. Wear whatever shoes fit you well.