import numpy as np
import h5netcdf

filename = "mask_and_scale_float32.nc"

with h5netcdf.File(filename, 'w') as f:
    f.dimensions = {'x': 5}
    v = f.create_variable('hello', ('x',), dtype=np.uint16)
    v[:] = np.ones(5, dtype=np.uint16)
    v[0] = np.uint16(65535)
    v.attrs['_FillValue'] = np.uint16(65535)
    v.attrs['scale_factor'] = np.float32(2)
    v.attrs['add_offset'] = np.float32(0.5)


import xarray as xr

v = xr.open_dataset(filename, mask_and_scale=True)['hello']
print(v.dtype)