You're talking about the headgaskets - on most vehicles, but especially Subarus, that's an engine-out job to do correctly.
The valve cover gaskets are very simple and do not need to be engine-out to get it done right, it's just a bit tricky. Downside is that oil leakage can occur from either the headgaskets or valve cover gaskets, so it's quite common for valve cover gaskets to start seeping, get repaired, only to have oil leaking out of the headgaskets next.
If left unchecked, the oil leak from the headgaskets will eventually include coolant and compression loss from headgasket failure, and if that's pushed at all, there's a good chance the water contamination in the oil will take out rod bearings... or you'll get the 'subie triple play' and after paying for an expensive engine-out headgasket job, you'll change the oil once or twice and a rod bearing will spin while you're merging onto the freeway. With any of the turbocharged EJ Subaru engines I've long espoused 'if it needs headgaskets, just rebuild the whole longblock' as a buy-once-cry-once sort of solution.
Then again, back in my speed shop days, we kept a shelf-stock built 2.5L STi longblock with Manley rods and pistons so we could have a 'fixed in three days' option for all the various WRX's and STi's that came in needing a fresh engine. I've done a LOT of Subarus. Which is bad because things like rod-knocking STi's show up on FB marketplace and I think about fixing & flipping it, and I do NOT need any more car projects!
Rudely getting back on-topic - the car market is in a weird space right now where spending a few grand fixing an otherwise known solid vehicle is a better choice than it ever has been.
I agree with @
SS90 in that too many shops that say 'it cant be fixed' really should be honest and say 'we can't fix it at all' or 'we can't fix it and make any money'.
I'm pretty convinced that you can find a decent off-road 4x4 shop that does suspension lifts and chassis fabrication, and they can install whatever frame reinforcements etc you need or re-fabricate whatever part of your truck is failing. It'll probably be a four-digit bill, but it'll never fail again. Might be cost effective to drop some fresh Bilsteins in there while you're at it, too.