you can still go 11 speed with a 10 speed hub.
The new R8000 Cassette in 11x34 ratio will fit a 10 speed hub. Anything under 34 you will have to use a dedicated 11 speed rear hub.

There are other way to make it work but is more of a hack. (ie using 10 cogs with a 12T lock ring)
Otherwise EDCO monoblock cassettes will work, but the shifting performance is not the same as shimano.


Depending in your crank setup
At 34T You will will need a GS rear Derailleur. You might be able to get away with a SS if you use a Wolf link.