This site is pretty helpful. You can upload an entire csv file of latitudes & longitudes, and it will process the elevation data to an output file.

https://toolbox.nextgis.com/t/deminpoints

For the elevation dataset, you can choose between the following: GMTED2010 resolution- 7.5 sec (about 250 meters), GEBCO resolution - 15 sec (about 500 meters), ALOS World 3D - 30 meters.

I just used it to generate elevation data for lat/long coordinates for ≈ 42,500 US zip codes. It took a bit longer than expected, but they have an option to notify by email when the process finishes so you don't have to sit around waiting for it.