💅Latest Telegram sources revealed an experimental Sticker Editor that may be available in future versions.

👀 Latest Telegram iOS sources reveal more info about upcoming Bot API update I've found a week ago.

Connection between bot and Business user

getBotBusinessConnection(connectionId: String)
BotBusinessConnection(flags: Int32, connectionId: String, userId: Int64, ..., date: Int32)

Flags contain info about bot permissions like "can_reply" and etc.

Interacting on behalf of Business user

updateBotBusinessConnect(connection: Api.BotBusinessConnection)
updateBotDeleteBusinessMessage(connectionId: String, messages: [Int32])
updateBotEditBusinessMessage(connectionId: String, message: Api.Message)
updateBotNewBusinessMessage(connectionId: String, message: Api.Message)

As expected, Telegram Bot API will send an update when Business user connects to the bot.
It looks like Bots will have separate methods/parameters to send messages on behalf of the Business user.

Interesting fact, API supports connecting multiple bots to one business account.