I use an Oura. I agree with the comments above that it does Ok at best as an activity tracker. It does usually pick up moving activities, even biking and things like doing chores, yard work, etc. But it does not pick up my stationer trainer rides at all. And the daytime HR on the new generation is virtually useless.
(FYI - I bought a Wahoo RIVAL watch and it does a great job of picking up HR from my wrist. I stopped even using a separate HR monitor on workouts because it was so consistent - and means I can have one less device to deal with.)
But I digress . . .
I do like Oura as a sleep tracker. I found it very helpful to pinpoint things that were compromising my recovery and sleep at night and have changed behaviors as a direct result of it. I never take it off, and I manually add my TR workouts just so I have a single source of all my general activity. As noted, it is not a medical grade device, but it seems to at least be consistent, so my trends are reliable. (And it generally relies on trends, not absolute values.)
I can’t strongly recommend upgrading to Oura “3.0” if you already have the older one. I don’t really get any added value from having dropped another $400 for the new one.