A lot of noise was made about the iPhone having an eSim, but some may have overlooked Google’s in the Pixel 3/3XL. According to Google you can swap on the fly from your current sim to eSim.
You can use the code to switch the SIM cards.
*#*#SWITCHSIM#*#* same as *#*#794824746#*#*
According to the Google rep it can be “messy” constantly swapping from sim to eSim. To me that tells me that the software is still a work in progress. But if you have a Project Fi account as well as another carrier, your Project Fi can be your eSim account and the other carrier your regular Sim account.
I am hopping to see this expanded on in the future where I can swap between my eSim and Sim much easier than having to remember a dial pad code. And would like to also see the eSim expanded to include major carriers.