Disclaimer: don’t know anything about the aircraft type and have no Boeing experience.
Do I see this wrong or does it look like engine #1 is at -a lot- more than idle thrust during that landing roll?
If so possible causes? Selecting reverse on both engines with the reverser not deploying on #1? Other tech failures that prevented the engine from going to idle?
Or maybe I saw wrong…

Not likely - an earlier post said this had PW2000 engines - FADEC. While nothing is impossible, it would be very unusual for a FADEC engine to not go to idle if the thrust lever is at idle.
Pilots have been known to inadvertently nudge the thrust lever of one engine above idle while deploying the thrust reversers on the other engines - however I've only ever known that to happen on quads (small hands miss one reverse lever) - hard to imagine that happening on a twin though.

A310 accident with S7 back in 2006. One T/R was INOP on MEL. “1.5 seconds after touchdown, Captain Shibanov set the reverse thrust lever for the right engine to the reverse mode. The right engine correctly went into reverse thrust mode. The reverse thrust lever for the left engine was not applied.

Consequently, during the time the reverse thrust lever for the right engine was being moved forward (to reduce the reverse thrust), captain Shibanov unintentionally moved the throttle control lever for the left engine forward (increasing forward thrust) while moving the reverse thrust lever of the right engine gradually up to the stowed position and remained in that position until the time of colliding with the barriers.”

The slope probably fractured the fuselage, as shown. Airfields such as this can be downright dangerous.

Looking at the latest video on Reddit you can notice the sudden deceleration just before taxiway K and that's when the smoke from the main landing gear appears (skidding?). Again, could it be that they thought they could vacate so not to get stucked on the runway and applied heavy breaking?

Interesting - I'd not heard of that one (probably since it was an Airbus). Certainly fits the scenario of what happened to this DHL 757...

https://cimg3.ibsrv.net/gimg/pprune....b6673f3e31.jpg
FR24 plot of the aircraft's trajectory after landing. Is it coincidental they lost directional control approaching K, or were they trying to exit the runway at K and lost control as they were doing so?

Reverser not deployed on #1 (i.e. FWD thrust) due loss of hydraulic #1 and (sounds like) lots of reverse on #2 would make it near impossible to maintain directional control much below 100 kts as rudder effect is lost.

Perhaps out of habit, and in the heat of the moment the pilot attempted to utilize nosewheel steering to steer on to taxiway K. Nosewheel steering is inop with loss of left hydraulics,(assume PTU inop) so he panics when the steering doesn’t respond and begins braking…I know this is complete conjecture, but it could be a possible scenario.

Having read so much about aviation incidents over the years, I have come to the conclusion of: If it can happen, it has happened somewhere. It truly is amazing how many accidents and incidents have happened over the years and how many have been forgotten.

If it’s at all like any other Boeing I’ve flown, that is unlikely, especially on a dry runway. You can dispatch with one TR U/S and following an engine failure you would only have one anyway. That means every landing with a TR U/S or RTO due EF would leave the paved surface, which doesn’t happen. The only time I’ve seen directional control compromised was a low speed abort on a contaminated runway, and that was due to one engine being at full thrust and the other failed; once the power was brought back on the live engine it was controllable again.

I don’t know what happened here but it does look like a more complex issue than a simple loss of one hydraulic system. I have operated to MROC and generally briefed that Liberia can be an option if it isn’t a time-critical emergency, as it’s at sea level and you should be able to land into-wind, rather than doing a dodgy approach or accepting a limiting tailwind if you don’t have RNAV auth for MROC. I’m sure the DHL guys would be aware of that, so something caught them by surprise, I guess...

Full reverse on one engine with the other engine at forward idle is controllable using rudder only down to ~60 knots (which, not coincidentally, is the speed at which you're supposed to be down to reverse idle). That's actually a regulation and gets demonstrated during certification.
If the engine in forward isn't at idle (or shut down), all bets are off...

Looking at the image it certainly is possible that they tried to take the high speed. I constantly have to tell F/O's to roll through when they use idle reverse and LO a/b then try to take the high speed at 70kts. So if a crew is conditioned to do that then they will just follow their instinct even in an emergency.

“Fly Jamaica flight 256 suffered a runway excursion after returning to land at Georgetown-Cheddi Jagan International Airport, Guyana.
The aircraft, a Boeing 757-200, departed Georgetown Airport at 02:09 hours local time. After departure the flight reported an issue with the hydraulic system. The climb was stopped before reaching FL200 and the aircraft turned back to Georgetown Airport.
The aircraft touched down on runway 06 at 02:53 hours. It went off the runway and came to rest across the airport perimeter fence. The aircraft sustained substantial damage. The right-hand main landing gear had broken off, and the no.2 (right-hand) engine pivoted forward and upwards. Six persons were injured, according to local media. An eighty-six-year-old passenger died of her injuries on November 16.”

Unfortunately, no report has been published(that I can find) on what happened.