How would I get an altitude map of an area from a satellite?

Question

I have found code which returns a single lat long point, but it takes about 1s per point. I would like to get an altitude map of an area between 2 sets of lat/lon coords. Ideally not with the googleapi because that requires a key.

My code (which I stole from another post) that gets a single lat/lon point:

import requests
import urllib
import pandas as pd

# USGS Elevation Point Query Service
url = r'https://nationalmap.gov/epqs/pqs.php?'

# coordinates with known elevation 
lat = [48.633, 48.733, 45.1947]
lon = [-93.9667, -94.6167, -93.3257]

# create data frame
df = pd.DataFrame({
    'lat': lat,
    'lon': lon
})

def elevation_function(df, lat_column, lon_column):
      """Query service using lat, lon. add the elevation values as a new column."""
      elevations = []
      for lat, lon in zip(df[lat_column], df[lon_column]):

          # define rest query params
          params = {
              'output': 'json',
              'x': lon,
              'y': lat,
              'units': 'Meters'
          }

          # format query string and return query value
          result = requests.get((url + urllib.parse.urlencode(params)))
          elevations.append(result.json()['USGS_Elevation_Point_Query_Service']['Elevation_Query']['Elevation'])

      df['elev_meters'] = elevations

elevation_function(df, 'lat', 'lon')
print(df)
df.head()

Which returns:

       lat      lon  elev_meters
0  48.6330 -93.9667       341.14
1  48.7330 -94.6167       328.80
2  45.1947 -93.3257       262.68

How would I get an altitude map? Not using this because this takes way too long.