We've worked on this before...
Here's a thread you might be able to get a better idea as to what to get...
https://www.fordfiesta.org/threads/welcome-newcomers-please-introduce-yourself.850/post-22330
To me, the places left to install a sensor on the Fiesta are less than it's worth unless you can find a sensor that can take a physical measurement for the smaller places - unless you drill, break a line or install a fitting to tap - meaning that Oil pressure is possible, if you use a "tap" but Water temp requires a fitting and an adapter to splice one into an outlet hose. Heater Hose splice can provide a possible tap point but you'll need room to mount it. Remember, if you try to tap into even the Oil cooler line- you won't get a "good reading" until the thermostat opens and the heat from inside finally flows out so you can get a reading, and unless you run the heater all the time, that hose won't let you see much to display until you turn the heat on to make the coolant flow thru that hose.
So what I find at local stores for physical sensor readings - unless they are electrical - they won't work on the Engine - the holes left to mount them are either too small or in the wrong location.
Now if this was a Chevy - Scion or older Ford using USA-cast blocks - we'd have something to help you but the Fiesta doesn't provide that - unless you have Electrical senders - not physical tube or bulb sensor that requires immersion or bolted fitment. The size of what I see on store shelves doesn't make this possible and there are "aftermarket" but being Foreign and mostly overseas - Amazon and or eBay might provide you a means to locate something exotic but as far as what I've seen with local suppliers - these newer units make me question their ability to provide fitment.
View attachment 9631
The image on the Left is enlarged to show texture...
The one on the Right is - it's on an engine block with lots of its Emission
lines and hoses removed (e.g- pulled out mounted on a stand)
The device next to it is a spark plug and it's heat shield shield canister
A good example would be Speedway Motors on Amazon, they provide adapters to help you fit a mechanical bourdon tube unit to basically bolt onto a hole but that hole size looks for 12mm X 1.5 pitch - but the standoff result is about 2 inches off the motor - so it's going to have to wait for that adapter to transfer the blocks heat thru it into that sender tube - so it may not be as accurate as you want it to be - so you may need to make some hard choices.
If you're looking for accurate - the physical/mechanical are the way to go, but they don't interface well with the newer smaller blocks and their clearance issues, on top of the fact that 12mm holes on the block are used mostly for the motor mounts and are well away from any sort of sources you can use to get any worthwhile readings.
The other units shown on Amazon like Dweekly - offer the Electrical style and can fit holes with single wire installs but you're stuck with electrical powered and some units are not regulated well and require pure feeder power so any noisy lines will get you lousy erratic results.