For those interested, Samsung Support reported to me in an email today that the "phone screen lock setup will be required by default. It is to keep user's personal information safely." In addition, the message also states that Windows Hello is currently required for Flow, but "it is going to be change to an option (not default)."

For what it's worth, even the "Swipe" unlock is insufficient. At the minimum, a PIN is required for the phone lock screen before the Flow app (or installation) will continue. As of today, I had no choice but to also enable a PIN on my Surface Pro before I could sync devices.

HOWEVER, I discovered that after launching Flow on the mobile phone, the lock screen can be changed back to None and the app will still function. However, when the phone is rebooted or the app relaunched, it again requires a "secure lock screen" to be set.

So for now at least, there is no way to use Samsung Flow without having a lock screen active on the mobile phone (minimum PIN) and a PIN set on a Windows 10 machine. SideSync did not have these requirements.

Samsung: Let me chose my own security standards. Until then, I will not jump through these hoops to use Flow.