An aftermarket head unit will require a trim kit which will remove pretty much all those buttons you are asking about.  Steering wheel controls can be retained, but usually require additional install steps and equipment.   Some higher end models of the Tucson have an external amp which complicates install of after market head unit - requires running more wire or additional hardware. 

Aftermarket head unit can definitely be added and be awesome.  I've been considering an aftermarket head unit for my 2016 that has Carplay and Android auto, because aftermarket head units have support for wireless carplay and wireless android auto.  Definitely make sure you get one with wireless support if you go with an aftermarket head unit!