Since the link is published in the echo, only those who read this conference will be able to follow it. In addition, we can always change this link or even disable it.
The publishing the invite link the way you devised seems fine. I was just trying to wrap my head around it being private, yet not - kind of. It still seems to be a fine idea to leave it private and not findable on Telegram. You have basically started a promo campaign using the bot. Reaching the landing page is cool - especially since it utilizes the icon and the description there.
--- tg BBS v0.6.2
* Origin: Fido by Telegram BBS by Stas Mishchenkov (2:460/58)