Interesting to see the SDK making chat/bot integration simpler, but there's a whole other dimension to Teams integration that this doesn't touch: telephony.
The company I'm at has been been building call analytics for Teams since 2021 (QueueMetrics Live). A long-time customer migrated their entire phone system to Teams during the pandemic and asked my boss if we could follow them there. We said "in principle, yes": the Graph API exposes telephony events, so it seemed doable.
It was doable. It was also far harder than anybody expected. The Graph API gives you raw call records, but it doesn't model concepts like "wait time in queue" or "lost call" or "failed agent attempt", and whet it does, nowhere it written HOW. You have to reconstruct those from sequences of low-level events. We ended up building the whole processing pipeline in Elixir because we needed to handle the real-time stream reliably at scale. After a long beta and a few million calls processed, we got to GA. I was dabbling in Elixir at the time, I put it on my CV, and it was noted. In a sense, I owe Teams my current job (though I ended up on a different team, so I'm mostly referring coffee-mug lore here).
We set out to track queues and auto-attendants (that's our bread and butter from the Asterisk world), but we discovered we were seeing everything — inbound, outbound, Teams-to-Teams, even calls with other companies with their internal ids. You can get a complete picture of someone's telephony activity regardless of whether they work in a contact center or just use Teams as their phone. Most of the boring config (names, groups, codes) comes straight from Graph, which is nice.
Like it or not, a lot of enterprises are quietly moving their entire communications (including telephony) to Teams. When they do, they lose the monitoring and analytics they had with their old PBX. That's a real gap, and the Graph API — despite its limitations — gives you something to fill it. But I have a feeling that "3 lines of code" won't cut it. :-)