2016 Possibly blown head gasket

Try swapping the #1 and #2 coils to see if the misfire moves to cylinder #2. Blown head gaskets are rare on gen 4s.

That picture of the underside of your oil cap does not alarm me - it could easily be normal varnish.

 

any coolant loss?

 

this does not say "head gasket" to me, especially on a 2016. more likely an ignition system problem-- i'd replace your coils and wires too and see if that resolves it before looking at the HG.

 

Do you know the code? They can point to specific cylinder(s). If so try post #2 suggestion, swapping coils/plugs between cylinders.

 

You shouldn't be able to see oil when you take the oil cap off. If you do see oil, there is too much oil in the car because everything is supposed to drain into the pan. There should be nothing under the valve cover where the cap is. What you are probably seeing is varnish which can be various colors, mostly dark though.

 

That looks like varnish to me and the light streaks, I would guess, are from the end of the funnel scraping it off. Another symptom of a HG failure on a Prius is usually white smoke from the tailpipe. The HG usually fails between the water jacket and the combustion chamber.

I also think it would be smart to try swapping around the ignition coils to see if the code moves with the coils.

 

How much oil would have to be in the engine to see it poling under the valve cover

 

A lot. I've heard/read mechanic horror stories where owners just kept adding oil instead of doing oil changes.

 

Some call these sales opportunities