I'd totally agree with you on that - there's really a lot of marketing going on. I noticed with my nephew that less is just more 😅 To be honest: lukewarm water and a decent diaper rash cream for sore spots, that's it. That's the core of everything. Your 3-month-old son has super sensitive skin and he really doesn't need all the heavy chemicals. All those special baby soaps? Totally unnecessary and can actually be irritating. Lukewarm water does the job completely, seriously.
You can skip the baby oil if the skin isn't dry. Wet wipes are practical when you're out and about, but I'd be careful there too - they often have preservatives and stuff. If you're at home, just wash with water instead. A good diaper rash cream (zinc-based or something like that) is really the only thing I'd recommend having. Not as a preventative every day, but only when the skin is red. Otherwise you're just making things worse because then the skin can't breathe. Trust your instinct, not the marketing 💪