I got the PLX wideband and gauge and I'm very happy with it. I asked the same question here and that was the recommendation. Well worth the $$. It also gives you the option to effortlessly connect it to an aftermarket ECU if you ever go down that path. It has a range of different options as the gauge itself is interactive and can show you voltage and allow you to log the data over a certain time period. You definitely get more than just a basic wideband gauge at similar prices to competitive wideband gauges.

https://www.tpl-au.com/product/PLX-0106/C6AFRG4/DM-6-52mm-%20-SM-AFR-GEN4-Combo?gclid=Cj0KCQjw0YD4BRD2ARIsAHwmKVlgrLlzEUJ1n9zxi0awqR2ILwnVf8KmOUilb2PC4eRy8Tu7PIAoya8aAp0lEALw_wcB

The 02 sensor should be placed 600mm+ downstream from your turbo. Any exhaust shop worth their weight should understand this and be able to sort you out.

Be sure to keep the wires away from your exhaust by either using zip ties or other cable ties and clips.

I used this cheap and basic gauge cup to hold mine, if they don't fit snug you can just wrap some electrical tape around the gauge until it is. From memory I had to drill the hole at the back for the wires to make it wider to feed the connector through - Easy enough to do. These can swivel up, down, left and right. I set mine up to just clear the glove box lid when parallel/in line with the hinges and just rotate the the gauge cup to be in my view when the glove box is open.

https://www.ebay.com.au/itm/322590660347

I have minimal electrical knowledge and experience and I don't remember having any issues wiring it all up. I installed the gauge in my glovebox as advised from @timbo and I'm glad I did (I think networking all the wires to the glovebox was the most time consuming part). As Tim suggested, having the gauge always changing colours and values is distracting/annoying when your driving, especially at night.