I don't have much context on them, but when a company is suing another for IP theft, they will have to prove it. Did they take any patents? Similar UIs are not patentable in many countries. They should show that both apps have similar code signatures of binaries. Maybe an advocate will be able to explain this better.
Oh it isn’t just the app. Essentially, oura created an entire industry of ring based wearable fitness trackers. Similar to that, ultrahuman is an Indian ring based wearable fitness tracker.
Ultrahuman recently targeted the US and hence this happened.
TLDR: Hardware not software
Then it boils down to how similar is the hardware. Unfortunately I don't know enough to comment on that regard.
The funny thing is he thinks he's responding and not reacting.