built a similar prototype on Telegram at first myself. Quickly ran into the same two walls you've nailed here.
first - field research across a handful of Indian manufacturing hubs (Nagpur, Bangalore, Noida, Mumbai) confirmed that Telegram has virtually zero business activity for these SMBs. whatsApp is where the invoices, quotations, and actual handshake deals happen. It's not just preference - it's workflow dependency.
Second - discoverability. getting a Telegram bot in front of a business owner requires them to actively search or be directed. WhatsApp, on the other hand, lets you run CTWA ads that drop them straight into a conversation. that's a fundamentally different funnel. the ad itself becomes the hook, the message thread is the landing page.
Interesting that you mention a manufacturing client already live on it, sharing invoices and quotes through the agent. that's the exact kind of transactional back-and-forth where the medium matters more than the bot's sophistication. WhatsApp's conversational interface already validates the behaviour - you're just automating the response layer.
Curious whether you've seen any friction around attachment handling or multi-language support in those invoice workflows. That's where the left-brain metrics and right-brain UX tend to collide hardest