Whether there is voice or not is just a matter of what you want to buy. Both data-only and voice-enabled are available from any of the majors (Vodafone/NOS/MEO). For banking purposes and the like you will want a voice-enabled one so it is “fully real”, I imagine.
Your husband is incorrect, iphone seamlessly handles having multiple voice lines as well as multiple data, if it is a newer one that can handle eSIM. I have a 13, with my US plan on eSIM and VodafonePT on real-SIM. I could have done it the other way, you can get eSIM in PT if you like, or have 2 or more eSIM and no physical SIM. You need to learn how to drive it correctly is all - there’s a few things not quite obvious. However all the tools are there to manage the situation (e.g. “I want to make this call through number”, “this call is coming in from PT and I am in the US, I do not want to bankrupt myself so I will not answer it”), and there are guides online I imagine. I manage this fine with my iphone 13, I imagine others here do the same.
If you don’t want to go to PT to get a SIM, you can also contact a provider such as OneSimCard which provides an Estonia-based SIM but can give you a live PT number as well on the same SIM. I have used them in the past. They can even give you a “banks recognize us as real for SMS purposes” US phone number on the same SIM, purportedly.