Boundaries and advice I didn't ask for
Show your support
Let him see you read his messages, then dont say a word, if he asks if you read his messages tell him you been busy. You can also do what amber said ^^ that is good one as well. You have already tell him you are prepare, either he wantsnto be involced or has insecurities based on your upbringing, but this isnyour experience, not his. And he should know better. Dont stress yourself and dont tarnish the relationship with him, so just try to avoid conversations and make yourself "busy" when he wants to talk.
Quite frankly every parent is winging it, it just depends how many attempts it takes to find the solution. One solution doesn't work for everybody but you'll find what works for you. That same solution may not work the next day or the next week but we adapt. Perhaps just keep your responses vague - "I'll grow with my baby" or "I'll be responding to what my baby needs". Even just defining a mother's intuition to him. This is your experience, don't let other people tarnish it.
People seem to love giving advice, my favourite thing is everyone I know says "every baby is different" whenever I mention research and the ways I have prepared myself. As if that doesn't make their advice just as useless😅 I don't really have advice except that I've found it's easier to look like I'm listening while in my head treat it like talking about the weather during a drought. I think sometimes people don't know what else to talk about, they're trying to be involved, and it shouldn't cost you your boundary but I've tried to focus on that to be understanding, and I walk away when it gets too much and use a random pregnancy symptom as an excuse