I took part on the beta for the s7 edge back when it got nougat and it was a great experience. I would definitely do the same for Oreo on the note if they decide to beta test for it too
I Beta tested the S7E as well. No issues whatsoever.
I have been checking the past couple of weeks for the Galaxy beta app. But I think it's nowhere to be found until beta testing for the Note8 gets closer.