Are the Portable Induction Cooktops compatible with stainless steel cookware?!

I just don't want to buy one and waste my $$$ in vane since I only use stainless steel cookware and I heard that it must be "magnetic"? Can you explain that?

Can I still use stainless steel cookware with a double portable induction cooktop?

Also can I place bigger stainless steel pots? Because I have a 12 inches steamer that will not fit the circle mark where you have to place the pot.

Thank you.