WTB plastic engine covers underneath?

ebay is your friend, for both oem and repro covers. The full under-tray/engine cover is somewhat spendy, in the $240 area, shipped. The front cover (below front bumper is in the area of $40, shipped.

 

Here's an engine undercover, don't know about the others you need, maybe salvage yard.

13 2013 Toyota Prius Lower Engine Cover - Body Mechanical & Trim - Action Crash, Front - PartsGeek

 

There's nothing missing in your second picture, that's the engine under panel, and it has several openings. For comparison, here's a pic of ours:



In the first picture, what's missing is a flap portion of the engine under panel, at the engine oil pan. This portion is often unfastened and bent back at it's "hinge" by service departments, and is prone to break off, due to the thin/brittle nature of the plastic used. Basically a fail by Toyota.

The simplest way to restore the whole thing (as mentioned above) is to spring for a complete new engine under panel. The flap that's broken off will also require several fasteners, that more-n-likely will be gone. That said, there's a possibility more of the fasteners are knackered or missing, best to assess.

Here's a snapshot from the attachment inset picture, you'll need two #5 (larger, grey headed fasteners) and the two fasteners and spanning piece of item #4:





There are aftermarket versions of the engine under panel available, for around $50. They'll be missing the interior insulation pieces, and there's been comment about uneven quality and some fit issues. That said it'll probably do.

Me, I'd get the official Toyota one, then never use that flap again, always remove the entire panel (it's not that hard), and wash the plastic fasteners whenever they're removed, in hot/soapy water. Doing all this, the panel should last the life of the car. I've done all the oil changes on ours, about 12 so far, following this regimen, and no problems.

I'll attach a diagram of the panel and the fasteners, with part numbers. There's a few typo's in it. for example, in one place the type "5" fastener references "thinner material", and in another it is "thicker material". The latter is the case I think, it is a heavier fastener, the one with grey centre piece. Also, the main picture id's some fasteners within the inset circle as type #3, then in the inset they're id'd as #5. Again, the later case is correct.

Bottom line, there's (11)-#3, (2)-#5 and the (2)-#4 with tie piece. With the latter, if you always remove the whole panel, you never need touch those.

As far as I know the part numbers are correct. Like a lot of Toyota documents, it's cumbersome, but you can muddle through.

 

You could try finding a wrecked Gen III Prius and pull it off of that.