So, fixed the rear sprayer.
Ensured the pump was working, slowly added more & more pressure until fluid/air came out the nozzle. Then tested bit by bit & found the obstruction was in the "last line" so I investigated.
The line inside the hatch was like a foot too long, and was sharply kinked acting like both a restriction and a bonux anti-drainback valve, haha.
Also, continuing being the antithesis to the "cosmetics oriented" previous owner I adjusted the steering joint so the steering wheel is straight. (no pics, envision a pic of driving straight & having the wheel be straight)