I picked up a nice four probe wireless thermometer today. The big advantage is a long-range base station with an actual display and controls that work without a phone app. I tried to connect their phone app to the actual device and it wanted me to set up an online account.

No.

Let me make this real fucking clear: THERE IS ABSOLUTELY NO GOOD REASON THE INTERNAL TRMPERATURE OF THE TURKEY IN MY OVEN NEEDS TO BE SHARED WITH A SERVER OUTSIDE MY HOUSE. NONE FUCKING WHATSOEVER.

"What harm is there if...?"

Wrong answer. This information is not relevant to anyone but me. Not every moment of my life, not every data point around me needs to go beyond my property line. This telemetry does not need to exist and it's taken for granted that it should by people who do not act in my interest.

@arclight I have similar feelings about IoT. Because my solar inverter required a cloud service and app, I ended up installing Home Assistant and a python library that acts as a proxy/trap for the cloud/API calls (works great and allows local control). This meant I later picked up a couple of motion detectors/light switch relays to replace some dead ones, but they run on ZigBee which is also all local (at least until the point you connect HA itself to the internet). Had no idea all this was out there until a couple of years ago, and it makes me hate cloud-dependent stuff even more.
@catch56 @arclight same negative feelings re: IoT and all other unnecessary, similar garbage. I actually have a connected air purifier that refuses to join the locked-down guest network reserved for things I don't trust. Perhaps there's an innocent reason for this but I suspect it's because it can't see anything else besides the gateway on said network and therefore doesn't have anything to phone home about. Have yet to find an alternative explanation.
@ianto_jones @arclight depending on the model and how desperate/brave you are, you might be able to replace the firmware. https://templates.blakadder.com/kogan_KASMTPRIFRA.html for example.
Kogan 5-Stage 3S Air Purifier (KASMTPRIFRA) Configuration for Tasmota

Configure your smart air purifier to work with Tasmota open source firmware.

@catch56 @arclight crazy, had never seen that before. Could at least offer clues into my brand. Thanks!
@ianto_jones @arclight not very clear from the link. The open source firmware for this kind of thing is called Tasmota. I haven't actually used it, but have some ZigBee devices that theoretically could use it if I could be bothered.