Datetime is mostly there. I think firefox and safari have yet to implement <input type=month> and <input type=week>. As for combobox, <datalist id=mylist> and <input list=mylist> is supported everywhere. However I would like to see the CSSWG focus on better standards for styling these, it is possible now using a lot of vendor-specific hacks, but is really annoying.

I’m gonna go ahead though and declare frontend validation (as good as) finished. the constraint validation API is amazing to work with (if you are not afraid of intercepting the submit event using JavaScript).