Is it reasonable to buy a new Apple Watch even though you own an iPhone 8? I own an iPhone 8 and I am considering buying an Apple Watch SE (GPS, 44 mm). I have had my iPhone for a long time and I have replaced the battery once. In my opinion, the iPhone 8 works perfectly well. But I have been contemplating about getting a fitness watch for a long time now and I really wanna buy an Apple Watch, but is it a good idea? Will it not drain my phone battery when paired? And will all features on the watch be available?

Question: Should you buy an older Apple Watch if you own an iPhone 8?
iPhone 8 supports iOS 14 which is compatible with watchOS 7, the latest OS available. Therefore all the features of the new watch will be available without compromise compared to a new iPhone.
Your iPhone battery will not have any noticeable impact caused by an Apple Watch. Bluetooth is required for phone/watch  communication, which can use some small amount battery on any phone, and may be more of an impact on an older phone with worse battery life due to age.