A poster named Joseph Corlett is a Pro who posts on this forum frequently about doing these replacements. He often replaces double-bowl undermount sinks with apron front sinks in stainless steel or one of the Elkay granite composites. It looks fabulous, and you do away with the cutout issue. You can do a search for the posts. Here are a couple: https://www.houzz.com/discussions/5702752/on-site-cutting-of-countertop-for-sink-hole#n=19

https://www.houzz.com/discussions/5038976/can-a-standard-double-sink-be-replaced-with-a-single-large-sink#n=16

Edited to add a couple of photos of double-bowl sinks he replaced:

Thank you! I have been following many of his threads. I guess I’m trying to get a sense of the most cost-effective approach. If we go the granite cutting approach, then do we hire a contractor and then decide on a sink? I’m trying not to put the cart ahead of the horse and figure out what steps I should take and in what order.

Try a Mr. Direct US1030 please.

No clips; (2) sink straps.

Four hours if you get lucky and are good.

A 3118 will work, but with some large negative reveals.

Thank you Joseph! This is exactly what I was looking for!