Mmmh so you will be trying to supplant the destination server with your own, with this emudhra leaked cert, to see what's being sent? Or how are you planning to do that? Just curious :)

Use my pihole to make the domain resolve to some machine on my LAN, then use this glorious new mitmproxy feature:

https://www.mitmproxy.org/posts/releases/mitmproxy-12.3/

Presumably just mitmproxy https://news.ycombinator.com/item?id=50189232 though this assumes the cert isn't pinned, which for IoT it may very well be (and probably should be).