I have a hero 7 black which is waterproof without a housing to a certain depth. The osmo is not and will need a housing. But I will say I would like an Osmo pocket as well. Hero 7 black has software stabilization which is good vs the Osmo gimbal which is supposed to be really good.
Mine came today and I wholly agree. It is complimentary not competition. I do have bias towards DJI's cameras. I'm not a fan of the extra wide Action Cam look. I appreciate the DJIs more cinematic approach.