SFC is a way to bond multiple connections very very easily. It has lots of clever stuff you can turn on, like WAN smoothing, Forward Error Correction and seamless hot-failover between those multiple Links. For a single link, the primary benefit of SFC is the ability to choose which location to break out to the internet from. The other thing I frequently do is turn on FEC to combat packet loss on a single link. The purpose of SFC is not privacy but application reliability using multiple links (and to a lesser extent bandwidth bonding).
OpenVPN has none of the clever multi-wan stuff as its not multi-wan aware and requires a non Peplink VPN service to be bought and paid for (NordVPN, ExpressVPN, ProtonVPN etc). There are more VPN service providers available globally. Most people use OpenVPN services for privacy purposes I would suspect (and enterprise networks access for those poor networks that don’t have a Peplink yet).
SpeedFusion VPN itself (with a private hub located in your own datacentre or run by you in a public datacentre) is more directly comparable to OpenVPN in that this can be more about privacy and used by enterprises to connect remote staff and their office locations.
Google I suspect.
Deleting locations turns it off. Also you can be more granular about which connections use SFC or not instead of removing the locations.