Samsung S8 trouble activating

After a complicated and convoluted process, it looks like my number has been transferred over from AT&T (I no longer have AT&T connection) - however, I do not have connection to Xfinity either at this point - it says Emergency Calls Only and there is no data service (i.e., I now have no phone). (Yes, I switched SIM cards. 🤣)

It has already been several hours, so it's not just a matter of time.

Customer support told me it "has not finished activating", stayed on the phone with me for ~10 minutes telling me every ~2min that it "hasn't finished" yet, then dropped me (and at that point it seemed that customer service is done for the night).

No help on the web site - it just says that my phone is "inactive", with no options.

Selected APN is one of the "Verizon Internet" (VZWINTERNET).

I tried adding an APN based on settings for Xfinity that I found on the Internet (e.g. https://www.apnsettings.org/us/xfinity-mobile/), to no avail.

Thanks for any suggestions.