I've looked into this, no dice as of yet.
What's funny though is that we now know that loading mods is possible because in the HatinTimeMods.ini, the devs left that config with a few mods that were set to disable.
I've tried dropping mods with layersFS into the HatinTimeGame/Mods/ directory and tried editing the HatinTimeMods.ini and pointed the mods in my mods folder at it and I couldn't get it to work either.
What is possible though is FULL graphical tuning. You can change every single setting. You can also uncap the framerate, but there aren't a lot of places where you can break towards 60 fps. In the SwitchSystemSettings.ini G4B even left a comment saying
; MotionBlurSamples was previously 9. MotionBlurSamples has no CPU cost, and on Switch we're CPU bound, so we can increase it to 13.
which is pretty nice.
You can also load Nyakuza Metro by swapping the map names. (I'm not really sure if it's actually fully playable.)