Maybe they could attach a cable and drag it up to a ship? I'm sure there's ways to help these people with joined effort

And with which equipment would you do that? Are there even submersibles with adequate tooling available in a small enough radius?

I've followed an OceanGate Titanic mission where a popular travel blogger was participating in and from what I understood there aren't many submersible vessels in the world able to go so low, let alone with functionnal tools. It is not like you can open the door to a diver for him to attach a cable, pressure is just too high.

This is barely on topic, but "there aren't many submersible vessels in the world able to go so low" caught my eye and I will use this opportunity to throw shade on the US DoD as partially responsible for the lack of such vehicles in current day. Yes, I'm pretty salty about this one.

The small submersibles used for Titanic the movie for filming the wreckage were Mirs* and a marvel of engineering for their time. However "[t]he level of technology flowing into the Soviet Union raised concern in the US and Rauma-Repola [the Finnish manufacturer] was privately threatened with economic sanctions."

* https://en.wikipedia.org/wiki/Mir_(submersible)

The French research ship Atalante is almost there:

"It carries the Victor 6000 autonomous robot, capable of descending to a depth of 6,000 metres, beyond the 3,800 metres of the wreck's position"

https://www.reuters.com/world/europe/france-send-ship-titani...

Last I checked on MarineTraffic Atalante was about 100NM away from site. Would it not help?

That is good but probably one of the best/only tools for the job. It is probably already too late though.

All that is still theory, we don't even know if the submersible isn't already destroyed.