I've loaded Public Beta on my iMac, my iPhone, and my Apple Watch. Then I decided to buy a new iPhone. Unfortunately, iOS 14 data transfer from the old phone to the new wouldn't occur. So I loaded the new phone manually. But then I couldn't download iOS 14 to it. Next, I took my watchOS 7 watch off my charger and discovered that it wasn't working; it wouldn't link up with my new iOS 13.6 iPhone. I finally just erased everything on my phone and did an auto data load from my OS 13.6 iPad. That went very well. I then went again to download iOS 14 to it and it loaded without a hitch. I went back to my watch and it had already made the decision to erase all and start from scratch. I then went to download the Apple Watch 7 public Beta and that went just fine. At this point, I discovered that my Apple Watch wouldn't unlock my iMac. I went to the Mac's security settings to get that working and received a message stating "Your iMac was unable to communicate with your Apple Watch". That's still an issue, but certainly no big thing.
The point being: Coronavirus stay-at-home time is perfect for loading and using these Public Betas. But if you're getting ready to return to the hectic life, I suggest you wait 'til this Fall (although knowing myself, it's not advice I would take). To me, these upgrades are worth the hassle. They make these devices a lot more interesting and certainly a lot easier to use.