For those coming here "but Facebook allows to search on channels"

Telegram? TELEGRAM IS SHOWING ALL MESSAGES! and allow to search channels in multiple ways and much better!
@NoComparisonTelegram53 (just as example)

Facebook: Yes, and NO! THEY DON'T SHOW ALL POSTS! and still ugly to discover previous posted posts!

So they exactly do like
@NoComparisonTelegram51