This is not only possible, but actually very easy. For most TVs I've seen, you can do it in a half hour using only a screwdriver.

I wrote a blog post about pulling the WiFi card out of my TCL R625, which should be pretty similar to the process for most other smart TVs: https://spencermichaels.net/posts/2020-03-16-smart-tv-loboto...

Would it work to set up an ESP32 as a WiFi access point that doesn’t route traffic? I wonder if the Samsung would detect that it’s an unhelpful internet connection and keep looking, or lock onto the bad network the user supplied.

There is nothing difficult about this. Modern TVs can be opened from the back to be repaired and are very modular. You can disconnect wifi antennas if you need to.