According to court filings, when Facebook was in the early stages of building its spyware VPN called Onavo Protect, it noticed that it wasn’t as effective on Apple devices as it was on Android. So Facebook approached a hacking group called NSO Group to use its Pegasus malware.
According to the court documents, it seems the Facebook representatives were not interested in buying parts of Pegasus as a hacking tool to remotely break into phones, but more as a way to more effectively monitor phones of users who had already installed Onavo.