Twitter allows you download your data. However, the list of following only contains the user id, not the username, which is basically useless if Twitter is down. This script takes the following.js from the data archive and fetch all the available data about each user (username, description, url, ...). You need to create an app to get the bearer …

fetch_users_data.py

import json
import os
import requests


# You need the bearer token, to get it, go to https://developer.twitter.com/en/portal/projects-and-apps and create an app
bearer_token = os.environ['TWITTER_TOKEN']

if __name__ == "__main__":
	with open('following.js') as file:
		data = json.loads(file.read().partition('window.YTD.following.part0 = ')[2])

	account_ids = [d['following']['accountId'] for d in data]
	chunk_size = 100

	output = []
	for i in range(0, len(account_ids), chunk_size):
		ids = account_ids[i:i+chunk_size]

		res = requests.get('https://api.twitter.com/2/users', params={'ids': ",".join(ids), 'user.fields': 'id,name,username,description,location,url,entities'}, headers={"Authorization": f"Bearer {bearer_token}"})
		assert res.status_code == 200, str(res)
		data = res.json()
		assert 'error' not in data, data
		for user in data['data']:
			output.append(user)

	print(f"{len(output)} users fetched, saving...")
	with open('following.with.username.js', 'w') as file:
		json.dump(output, file, indent=4)