> So to check if a string can be converted to integer with help of int() I should be using str.isdecimal() instead of str.isnumeric() ?

Yes, I think that's correct. The characters matched by `str.isdecimal` are a subset of those matched by `str.isdigit`, which in turn are a subset of those matched by `str.isnumeric`. `int` and `float` required general category Nd, which corresponds to `str.isdigit`.