Are you asking ... if AmE speakers use glottal stops when speaking?
we have no common way to write it.
Is it as strong as it is in some parts of the UK, where you will hear it in the middle of words like bottle and water?
It's common in American English, and I didn't know that we don't know about it!
I don't hear it in "can't," but it's loud and clear in "didn't"! (In parts of New England it's so strong it sounds like a hiccup. It's strongest in central Connecticut: DIH-ent.)
Is it as strong as it is in some parts of the UK, where you will hear it in the middle of words like bottle and water?
A friend who lived alternately in central Connecticut and Florida (her parents owned one of the Connecticut resorts!) talks like that.
The final phoneme in can't is usually a glottal stop. That's all that distinguishes I can do it! (spoken emphatically) from I can't do it!
In central Connecticut, there's absolutely no T in bottle - just that hiccup. I hear it here in Maine and elsewhere sometimes, too, but it's not as common.