Rasterio Tiling (working, but no scaling)

import rasterio
from rasterio.transform import from_bounds

with rasterio.open(source_path) as src:
    kwds = {
        'transform': from_bounds(*tile_bounds, tile_size, tile_size),
        'driver': 'PNG',
        'dtype': 'uint8',
        'height': tile_size,
        'width': tile_size,
        'crs': dst_srs,
        'count': src.count + 1
    }

    # create the output directory
    os.makedirs(os.path.dirname(output_path), exist_ok=True)

    with rasterio.open(output_path, 'w', **kwds) as dst:
        for i in range(1, src.count + 1):
            reproject_args = {
                'source': rasterio.band(src, i),
                'destination': rasterio.band(dst, i),
                'resampling': self._get_resample_alg_value(resample_alg),
                'dst_alpha': src.count + i
            }

            # can only specify nan nodata value on float32 and float64 input bands
            if src.dtypes[i-1].startswith('float'):
                reproject_args['src_nodata'] = numpy.nan

            reproject(**reproject_args)