This is what it looks like. It doesn't look much different than One UI 4/4.1 since it is the Alpha version. Only Tech reviewers have it like Max Weinbach, official public beta isn't out yet. More changes expected to come so don't be disappointed yet.
You're welcome. When you look in the banner right now, you can see the beta for Watch OS. The same thing will happen once they release the beta for One UI 5, there will be a banner and you click on that and find the sign up for the beta program. Sometimes they limit the amount of members who can sign up...so I would suggest to keep checking daily and sign up once you see the banner for it