esims or sims- what do I need

A physical SIM or eSIM is simply a way for you to connect to a cellular network and provider. It tells the network that you have an account. The 1GB is not a download but the amount of data you have paid for. Depending on the plan you select once that data is used up you may have no more data or data at very slow speeds.

Tethering essentially turns your phone into a WiFi hotspot so you can connect other devices such as another phone, laptop or tablet.

I used an Airalo eSIM for my recent trip. Easy to load on your phone before you travel and turn on when you arrive. I had a glitch at first - the eSIM needs to set to roaming to work. Once I figured that out, all was well. I will use them again. It is data only, but you can make calls using WhatsApp.

Whether you need an eSIM or physical SIM is dependent on your phone. Your phone may have two physical SIM spots, One Physical and one eSIM, or only eSIM. Your phone may only support one SIM as well.

Then, since your phone has service, and you already use one slot, so first, you need to determine with your carrier, if they allow you to use a second, or replace their SIM with another company. If not, then you are out of luck, if so, they will tell you which one you need.

Edit: As an example, I have no contract, my phone has one physical SIM slot, and one eSIM. Up until last year, my carrier (GoogleFi) used the physical SIM spot, and the eSIM was available. But now, they use the eSIM, so I would need to buy a Physical SIM if I needed a local SIM.