I have a Huawei, has most of the things you're looking for, except for the EKG's, but the accompanying app does support that so it is probable the new incarnation of it does do that (mine is v2). You don't need any subscription of any type and the watches will do most of the stuff on the watch itself. But you get enhanced functionality and history on the accompanying phone app. Hope this helps...
Happily collecting things all my life...