Transfer prepaid physical sim to prepaid esim - keep number?

Hi, I've received conflicting information about this so I'm hoping someone can help.

I'd like to change my prepaid physical sim to a prepaid esim but I need to keep my number. I was initially told I could do this, but then told that a number couldn't be ported from prepaid to prepaid.

I then thought I would switch carriers so that I can get an esim and transfer my number, but AT&T and Verizon only offer the esim on postpaid plans.

I'm almost due to pay again for a new billing cycle so I canceled autopay in the hope that I could then purchase a new prepaid plan instead, and transfer the number.

Any help would be appreciated!