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How old are you? How much time do you spend actually typing in a given day? How many days a week do you do that?

RSI is a real issue when it comes to typing. Especially once you've been doing it 8 hours a day for 20+ years.

But RSI is usually in the wrist and/or forearms, not the fingers themselves, which is what the OP is having issues with.
 
If you mean, make it angled. Saw a contraption on Amazon(that I am not finding at moment) the other day that stuck on bottom back of MBP and it had little things you opened that propped back up, similar to feet on normal keyboard that can be open or collapsed. Might look into something like that? If I find a link, I'll post it here.

Perhaps this OP?
Image

Suzy products for Apple Laptops also have legs.
 
It depends on what is beneath the keyboard. If I’m typing with a really soft puffy blanket under it, it doesn’t hurt my fingers. So I was wondering if there was something portable that I could always put under it so that it wouldn’t hurt my fingers.

You don't need to mash the keyboard like you want to kill it for it to work. A soft tap'll work just as well.

The problem isn't the keyboard, it's the way you type.
 
An option is to use a cheap rubber keyboard protector for the macbook pro. It softens the keyboard but you still get the feedback.
 
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