Most freehub bodies can do both 10 and 11 speed, so you might not need a new one.
Regarding the rear mech - not entirely sure how this works for shimano, but a 1x specific mech will keep the chain tension better.
You’ll need a new rear shifter to use the extra gear obviously.
And a new 1x (narrow-wide) chainring.
Cassette and chain are the same.