I have used Google Voice for my ‘business phone’ for years. It’s always been something of a terrible and inconvenient hack, but it was free, and it let me (at least theoretically) separate my work life from my regular life.
I use a dual SIM setup on my 11Pro (and my 2918 iPad Pro) while travelling outside of Canada. It works fine, but of course you don’t have the same number on both lines. That isn’t an issue for me because I use a data only service when travelling. It works very well for me.
I have a French eSIM and an Australian SIM. It’s all very transparent and iOS is very smart in figuring out on its own what to use where. My French number can roam, the Australian one can’t, and it very well picks on its own what data to give me. If it won’t, or if numbers get mixed, you can set which line to use which your contacts. It’s very convenient.