> Does Pegasus help governments read messages from Telegram? Signal?

Yes. It attempts privilege escalation and exfiltrates whatever message contents it can from multiple apps. Signal has some potential resistance to that since messages are encrypted in transit and at rest. The easiest weak link would be displaying message content in notifications, which is optional in Signal.

https://en.wikipedia.org/wiki/Pegasus_(spyware)

Interesting, thanks. I guess I'll carry on feeling marginally superior for choosing Signal over the others as my default, while remaining bleak about the overall landscape.