How to join my Telegram Bot to PUBLIC channel
Another way of "scraping the data" from several channels would be to listen to these channels with a Junction Bot aka Channels, Multi Feed Edge Bot, or alike. You just need to go to the channel info and share the link of the desired channel with the Junction Bot to automate the process of receiving new messages from the(se) channel(s). There are also other quite advanced ways described in their FAQ.
Multi Feed Edge Bot also seems to work O'kay, however, you need to follow these steps to add the redirection:
/add @TelespaceNews https://t.me/joinchat/AAAAAFIaTHjZp8ltykgwEQAnswer to your edited question.
It was possible to add a bot to a group/channel with just an invite link. This was achieved by allowing a bot to access the mtproto methods like messages.importChatInvite for private links and channels.joinChannel. However telegram patched this. However, you can still do this with normal user accounts! Since you are using python you can give this a shot. I can confirm the methods still work on Madeline Proto.
Till today, only the Channel Creator can add a bot (as Administrator or Member) to the Channel, whether public or private. Even the other Channel Administrators cannot add a normal member leave alone adding a bot, rather they can only post into the channel. As far as joining the bot via the invite link, there is yet no such method in Bot API to do so. All such claims of adding the bot to a channel by non Creator are false.