[new echo owner]

Besides take the pictures above what other test have your done to determine the condition of the engine? Compression test? Leak down test? Oil comsumption test?
Those test would give you some idea on how much it would take to repair your engine vs replacing the engine! Since the gas engine on the Priuse used more for recharging the Hybrid batteries and supplemental power, it might not need to be 100% to keep the vehicle operational!
Just saying!

 

[new echo owner]

Well, as far as I can find Toyota does not recommend boring or honing the cylinder walls. The cylinder walls are obviously damaged, and with no way to repair them there is no way to repair the engine.

Having said that, there are forged aftermarket pistons for these engines. However, they are $800 and up for a set and as said before, Toyota does not recommend boring the cylinders because the sleeve is very thin.

Which is why I asked what test have you done on the engine!
Doing those tests will provide you with the information; for example, if both compression and leak down tests give you good results, then don't even need to consider boring the engine.
Having said that, the vertical score marks can be worrysome; however, that can be determine with the leak down test!

 

[new echo owner]

Compression test on a hybrid is a bit more complicate than a regular engine, but in a case like yours, it would help you decide which would be a better option to go with.

 

[new echo owner]

Those numbers aren't too bad, considering the mileage of the vehicle, and how even they are between cylinders.
Didn't realise you are way up there! Have to ask, how is the weather up there? 🤣
Have to admit, not exactly familiar with doing compression test at high altitude! So don't know where the numbers should be on a good engine!
From what I can find online, compression test with those numbers are actually pretty good at high altitude!

Comparing to a regular gas engine, it is more work! 😁 Pull plugs, pull the fuse, jump the starter!

Usually, at least for one cylinder, crank the engine over until you get the highest reading, so you can have a reference number!
Your engine with those numbers, and not being the primary power source for the vehicle, I would say as long as it is capable of recharging the hybrid battery, the only thing you probably need to do is monitor the oil level. And maybe do another compression test again, 6 months or a year down the road, depending on how many miles you put on the vehicle!

 

[new echo owner]

Many parts of the country are getting colder than normal weather as well, not just high up there anymore. And according to the forecast, more cold and snowy days are just ahead.

Toyota consider 1200miles/Qt is normal oil consumption, you can't go off that to determine if your engine is using more than Toyota's accepted normal!