Instead of Telegram, go self-hosted for company related communication activity. See Gamers Nexus recent video on self-hosted discord alternatives https://www.youtube.com/watch?v=kpjcmXbmMVM
For encrypted group conversation over third-party networks use Signal, or Matrix which try to keep your conversations private.
The fact that Telegram has their support playbooks online, is interesting. Though I would call the following claim a stretch
> As a result, we have disclosed 0 bytes of user data to third parties, including governments, to this day.
