Not really: Samsung and LG both have awkward, limited one-hand modes, but not an elegant solution akin to Apple' Reachability. LG simply squishes the keyboard (not the whole UI) to one side--no help getting to stuff up top. And Samsung reduces the whole screen to a corner, making tap targets smaller and wasting the screen with ugly L-shaped black bars. And neither "solution" is ambidextrous.
Apple Reachability isn't some setting to dig for, it's ALWAYS present, and yet it takes effect only at the moment you need it, then automatically goes back to normal. It doesn't require a choice of left or right-handed, doesn't shrink anything (keeping it all easy to read and tap), doesn't look like a bug, and unlike LG, works for everything.