My son has a Galaxy S20 running Android, and he said to me recently he has been bullied for having such a phone because it's 'lame'. I tried to explain it's a modern enough and capable phone that can do everything the latest iPhone can do, sometimes even better. He claims all his friends have the latest iPhones and they shun Android.
I own an S20 too and tried to explain how you can side-load apps from F-Droid, bypassing Google Play, but he's too young (12) to understand such concepts. He just wants to play a few games, do instant messaging, and do casual surfing.
How do I convince him that this peer pressure is unacceptable and that iPhones are not automatically 'better' just because they're marketed as a premium brand are are nothing more than expensive jewelry?
There are a couple ways you can approach this particular issue.
1. You can capitulate to the demands that your child has, and get him an iPhone of some appropriate variety. You can attach some strings to this, maybe he needs to work or do something else and this can be his reward, or you could just give it to him. Sometimes it's best to pick your battles, and you could have a conversation with him about that.
2. You can continue as you have been doing to try and teach your son that the kids are wrong, and that he can be resilient against this kind of bullying. (I don't think I recommend this strategy)
3. You can tell some other authority figures about what's going on. The outcome of this will largely depend on who they are, and how likely they are to recognise/care about the bullying.
EDIT:
The most important thing is to talk to your son about this, and listen to what he has to say. You might think you're an expert on phones, and you probably are. That doesn't matter. Let your son explain how he feels, and work through a plan to make the situation better. Bullies prey on insecurity. Help your son understand what's happening and let him know that you are a person who can help.