Help decide what to do fixing 2 battery cells + head gasket? sell? keep?

I bought my 2012 Toyota Prius back in August of 2021 right when I moved to LA. I bought it 190,210 miles for about $6800. Now in May of 2022, it's sitting at 203,510 miles. It's my daily and I also put ALOT of mileage for work. Keep in mind this is my first own car that I bought on my own. I go out of town sometimes and this is probably the 3rd time that once I turn it on after sitting in my garage for 1 week/2, it starts making noise. But this time, I got all the yellow dashboard lights on with "check hybrid system" message on it. I went to Auto zone and got the replace spark plugs solution as well as P0303 cylinder misfires detected (which the shop mechanic confirmed I have 3 of them that have misfires), and the codes C1259/C1310 HV malfunctions.

Basically, my car's head gasket needs to be rebuilt completely due to the coolant leaking on the engine or something and the hybrid battery has 2 bad cells from what I am told. I was literally in shock because I went in March to get an oil change and got told I have a oil leak in the timing cover area, with low coolant and oil, nothing near to this degree. I went 3 weeks later to another shop to see about this oil leak and the severity since I had a mechanic guy from the dealer that I bought the car from who basically was gonna charge me $340 to fix this timing cover oil leak and then flaked. This other shop inspected and it basically told me there’s nothing to fix urgently rn cus it’s barely leaking and it’s be $1995 to fix with the right labor/parts but it’s not needed at all with the amount of oil leaking. With that being said, I went to the local shop near me in LA who gave me the quotes for the following.

- Head gasket (rebuild heads): price: $3500 + tax

- HYB Battery (2 year warranty, 1 yr warranty on labor): Price: $2284+tax

- A/C Filter (very dirty, was told that there were rodents under here probably when it was sitting in my garage, this alone is making me want to sell the car): Price: $39 + tax

- Sway bar end links: price: $236.56 + tax

- Rear shocks (blown) : price: $525.60 + tax

- Wipers

- Transmission service (fluid dirty): price: $139.95 tax

Now luckily, the shop mechanic who checked all of it gave me the number of his friend who is able to fix the head gasket completely for $2100 and can fix the 2 bad cells in my battery (the rest are completely fine from what he showed me on his reading) for $450. This totals it out to $2550 for repair on the two most important things. The guys at the shop said they can fix the other things for a lower costs if I decide to go ahead and fix the gasket/battery but it'd be stupid of me to fix it which I lowkey agree with them when I first got their quote. The mechanic friend was saying that the battery will be fixed, not completely replaced, and it could last 2 or 3 more years or 6 or 8 months who knows, he says from experience it can be either/or and from reading on reddit, it sounds like the risk is truly unknown.

Looking at my options, my dad said we could sell it after probably (the mechanic though was like why would u sell it if we just repair it) lol , the guy sounds like the head gasket getting completely fixed is the most important part which I do believe so, since I have 1 bad cell sitting at 14.03 or something and another cell he mentioned too but the rest are up to par at 16. To summarize, there's a $1400 difference in getting the head gasket fixed with the price $3500 from the shop (which the mechanic friend said will be fixed good as new, but from what he can tell it looks like mine has never been touched so idk if it will need all the other things like spark plugs, water pump etc). But with all the other things like the rear shocks etc, I'm looking to see how I can finesse selling the car after the battery/head gasket are repaired. Or what even is the best way to approach this honestly.

Any thoughts on replacing 2 bad cells vs getting a whole new battery? With my car at 200k miles, it's already having multiple issues after only owning it for 9 months. I'm thinking of selling the car and going for a Honda Civic that is much more reliable, I couldn't really get past the fact the Prius would have issues if I don't drive it for 2~ weeks. Keep in mind also, if I get these things repaired in next weekend. I will have to get all these other things fixed and I will be away in Europe for 17 days in June. I'm scared it will act up again only having fixed the battery cells and not the whole thing itself. Any advice on what to do would be greatly appreciated. My parents don't own hybrids and I dont know shit about cars except just reading on reddit about my situations.

Tldr: repair 2 hybrid battery cells and replace head gasket and sell it with minor exterior issue or sell it as is to avoid time wasting and throwing more money at it. Thank you!