You absolutely can't open complex sheets on the ipad still, I just tried a few and they're not functional. how do you open more than one doc natively? I'm still

You absolutely can't open complex sheets on the ipad still, I just tried a few and they're not functional. how do you open more than one doc natively? I'm still seeing online that it's not supported (using the browser doesn't count). And yeah, none of the extensions I use have a special iOS equivalent.