Your Apple Watch 8 is most assuredly capable of tracking body temperature (as part of sleep tracking), heart rate and blood oxygen as well as ECG. Not all options are available in all countries. No current Apple Watch is capable of taking Blood Pressure measurements. Whether Apple will ever figure out a way for a device which sits on top of your wrist and is not capable of exerting the type of force against veins required to take Blood Pressure, no one here could possibly answer. We are NOT apple on this user to user only forum and we have no inside knowledge of what Apple is working on for future releases.
My instinct tells me Blood Pressure monitoring is not something a watch is capable of doing. But that's just my guess. If BP readings could be taken so easily, one would think your health care provider wouldn't need to put a cuff on your upper arm, which constricts your arm to accurately read your Blood Pressure.
Please point out which other watch is capable of accurately tracking Blood Pressure. I know of NONE which can do that.