I use both around six SIM and eSIM cards but my main phone subscription needs a physical SIM card so I will not be getting the Duo.

Edit: Reply to nomel as I am rate limited

Cheaper than roaming cost. I have eSIMs for countries I frequently visit.

This is Europe. I can do a short walk and cross multiple countries borders. It's nice to have coverage everywhere. I just toggle my eSIMs for that. When I'm out on a boat trip and I pick up a Moroccan signal from across the Strait of Gibraltar I turn on my Moroccan eSIM so I'm not paying €2 per megabyte in roaming cost. When I get cheap gas in Gibraltar I switch on my Gibraltar eSIM and turn off roaming on my main line. When I cross into Portugal I switch to a Spanish provider since they give 15 gigabytes of roaming for free.