The Prius V was introduced for 2012, and discontinued after 2017 (apparently, once the RAV4 came out as a hybrid in 2015 no one wanted to buy the Prius V anymore).
The shoulder belt for 2C comes from the roof (yes, this is safe) – see here for how to use, connect, and disconnect this seat belt.
The Prius V’s center seat was a tough spot for many car seats due to its narrowness, the bump at the seat crease, and the significant amount of seat belt buckle hardware on both sides. If you need two rear-facing car seats side by side, we’ve found a rear-facing Clek Fllo in the center (install with seat belt + anti-rebound bar) and a Cybex Aton2 on the driver’s side (install with LATCH + load leg) works well. There doesn’t seem to be enough room for 2 car seats side-by-side in 2C & 2P as these seats are narrower than 2D (2D is the widest seat of all in this back seat).
Getting to the tether anchors is rather annoying – requiring you to have to slide the vehicle seat forward in order to access the anchors.