Smart plug sounds reasonable.
But as per IOT7712’s hint, I would also hook up an esp and see if it happens to use the Tuya MCU.
Even if it doesn’t use it, you might be able to read some useful data relatively easily (check uart debug), you have the button press option you mentioned, and you have 5v right there for power.
Although if the logic is 5v I think (?) it would be less likely to use tuya MCU? So double check that first.
Depends how much you feel like tinkering though.