If all this is an illusion, even the things in your head are illusions, so it doesn't matter if it's 'reality' or not. What matters is if they are useful illusions to you.

You can decide for anything if it has special meaning, or not. Some might see a chair and take it for granted as being a simple object. Someone else might see it in a metaphorical sense as a reminder to be supportive and comforting to others and have a purpose.

If you hallucinate an angel, and it helps you improve yourself, does it matter if there really was an angel or it was 'only in your head'? Is there a difference?

You'll never see proof of anything in life, everything is faith even "objective science." Don't worry about what's "real", focus on living consciously/mindfully and connecting with others.

The short, anticlimactic explanation of what you learn from psychedelics is that almost all cliche sayings are true. "Home is where the heart is"; "youre only as good as your word"; etc... read any trip report about what people realized, and you'll be able to find the appropriate cliche phrase to sum it up. They're cliche for a reason.

Psychedelics help you more to find the right questions, than they provide answers, but you might find that you already have the answers when you start asking the right questions.

The more beneficial effect of psychedelics is the breaking of habits/routines. After a trip, I might wake up and think "I usually get coffee, but do I want/need coffee?" Living mindfully gives you the power to not be a reactionary slave to your emotions. Make decisions not reactions.