My provider have feature called "Extra SIM". On single number you can have up to 2 extra SIM including main one.
How this works - all cards connect to cell network as single number. They share same plan as main card. If you call to that number all cards rings, once you pickup on some then calls are stopped to rings.
I remember a couple of years ago, I went with a colleague to a Telecom shop to clone his existing SIM card to use it in a different device, without cancelling the original one.
I guess it's an option you could try? /me-thinks
Data plan for both, voip app on both for the number you want to be called on. Enables you to also have a soft phone on the desktop if you’d like. I am partial to OpenPhone (no affiliation), but any voip service and app of some quality will do.
try limephone.io or google voice
Set up Google Voice so all calls are forwarded to both phones.
Carriers have the option to have a single phone number for multiple cells phones. In the US on Verizon, this feature is called “Number Share”. Most carriers have this under some other name.