xAI offers "Live search" option for API calls, which - as of this market's creation - has four possible content sources: web, X, news, RSS.

It can also be seen that Telegram and xAI are building some partnership. One of possible steps in such partnership would be that public Telegram channels are offered as an additional data source. Will it happen?

This market resolves YES, if at some point (before market closing) the xAI docs (https://docs.x.ai/docs/guides/live-search#data-sources-and-parameters as of now) list Telegram as an available data source ("in plans" will not count). It is not relevant whether I can actually access this functionality or how expensive it is.