Buy this. It was developed by DTech Dave and the guy who started EMTron, almost identical to the official EMTron one but without the big name pricetag.
https://hv-electronics.myshopify.com/collections/hv-products/products/hv-lambda-to-can-single-channel-module-with-pin-kit
I've also got two of these to install but haven't got around to working out how to wire up just yet.
https://www.msel.co.nz/epages/motorsportelectronics.mobile/en_NZ/?ObjectPath=/Shops/motorsportelectronics/Products/SENBOSTP10
Turbo speed is always a good one to monitor with EFR’s too.
Don't the flex fuel sensors usually have a fuel temp sensor as part of it?