I have a slightly different TV (TCL 43S425-CA), but I have the same problem. Such a shame. These TV makers could eat the lunch of even expensive gaming monitors if they just enabled computer monitor features for these things. A TV that can run 3840x2160@60 can also run 1920x1080@240, the signal bandwidth is the same. They really should unlock these features, even if they put them behind some kind of opt-in. I would pay to be able to have granular control of interpolation modes and to be able to use any refresh rate the hardware is able to support.
As it is though, there is no compelling financial incentive for them to do this, otherwise they would already have done it.
Does anyone know if jailbreaking these roku TVs to access the underlying hardware features directly is a thing?
I imagine it’s more complicated than that even if the bandwidth cost is the same it comes down to the response rate of the pixels, there’s a post on AVS where a user used EDID override to achieve 100hz at 1080 but said it was janky.