I picked up my i14 Pro Max yesterday and did the transfer with one small issue. The only esims that moved to the new phone were 2 from T-Mobile. I have 3 other esims that did not port to the new phone and it reported that "Transfer Not Supported". They are visible as a greyed out line in the "Add eSIM" of the new phone. One is from Flexiroam and they were contacted. They are going to work with me, probably sending a new QR code to allow me to transfer my data service. One is from Xfinity Mobile, which I converted to esim in anticipation of the new simless iPhone, and one from Bne, a data roaming carrier. I expect Xfinity to have a solution ready since they will lose customers if they cannot transfer from sim to esim users. Bne is not being too cooperative so far but it is probably due to a language difference. During the transfer setup I requested my esims be ported to my new phone I believe.

The only one of these that really matters is my Xfinity line, since it is a Verizon MVNO for $15 a month ($19 inc. taxes, total for both lines) with two lines as emergency service numbers. It only includes 1 Gb of shared data, but each line has a dedicated number, and works well. I got a $400 gift card on promo when I signed up about 6 months ago, so no loss if I need to just drop the service.