Although “smart TV “ is a loosely defined term, the current over-the-air EPG (electronic program guide) is more a function of the ATSC television standard. I have TVs that have EPG (can decode and display the guide from the OTA signal) but are not considered smart.
Nonetheless, I feel your pain. The TV that came in our motorhome built in 2019 is obviously ATSC compatible, but has no EPG nor is it smart.
The device linked in post #1, a standalone tuner, could suffice if the TV has the appropriate input jacks for connection. It would probably mean fumbling with an additional remote at times.
2020 Sunseeker 2440DS on 2019 Ford E-450, Trekker cap, Topaz paint