Neither the MPVZ4006GW7U-ND [Pressure Transducer] nor the 401-1963-ND [Pushbutton switch] seem to be in any of the DigiKey libraries.
However, neither are difficult to make - @Rene_Poschl has already linked to FAQ resources and, in fact, these two items would both be good starting points. You will always have to make some symbols. Even if you just use DigiKey as a supplier, they offer in excess of 8,000,000 product lines - there is no way that all of these will ever all come with a KiCad library entry.
It wouldn’t take long to make a symbol for the pressure transducer. It only has four connected pins and the symbol need only be a box with 4 connections.
PIN NUMBERS(1)
1 N/C 5 N/C
2 VS 6 N/C
3 Gnd 7 N/C
4 Vout 8 N/C
The footprint is a very simple DIP8 (there are also surface mount alternatives). This is a standard footprint which is in the library. At this stage I wouldn’t worry about a 3D model.
The switch is the reverse problem. You can use a standard pushbutton switch symbol and you need to design a footprint layout from the datasheet. These switches seem to be on a 5mm pitch square - so very simple to draw on a mm pitch grid. There may well already be a suitable footprint to use in the standard library - I haven’t checked but t.b.h it would probably take me as long to check as to produce a custom footprint. Again the resources linked will talk you through it.
Once you have done this a couple of times you will find it quite straightforward. I understand and appreciate that when starting out you would like the confidence that using a symbol & footprint that someone (more experienced) has run up. However, you potentially spend hours searching for an elusive and perhaps non-existent library when it really would be better to accept that some of the time you are just going to have to make one yourself and spend the time learning that this is part of PCB design - whatever EDA program that you use. When you accept that, the whole process becomes more productive. There are all sorts of scripts and wizards included in KiCad which make the whole process even simpler.