Answer to "Replacing the heart rate monitor"The teardown goes over how to remove that part but it also requires doing pretty much a full tear down to get to it and as long as that is the extent of the damage I have good news and bad news. Good news: It can be repaired! Bad news: I can’t seem to locate anyone who sells that specific part by itself. The teardown goes over how to remove that part but it also requires doing pretty much a full tear down to get to it.
Answer to "Dial on headband is not working"The headband works like regular gears so if it is not working it means the teeth of the band fell off the gear or the teeth broke off. With the size of the teeth it is not likely that is broken, so opening up the back should give you insight on what is going on and how to realign it.
Answer to "Main camera lens glass shattered"As far as the lens itself it appears to be the same lens and size as the pixel 2 which are available for purchase by themselves. The cameras come out relatively easily once you open the back panel, the teardown video covers this within the first minute. As far as repair of the lens, looks like we just need you to create that guide, but it look like it is adhesives from there.
Answer to "Have I been bugged?"If you are worried about being bugged then perform a factory reset and to wipe it completely. If you just received it then there shouldn’t be much in the way of data loss for you.