The last servicing mission to Hubble installed a connector to Hubble that can be used by Dragon to directly attach to the telescope. It's not a perfect match for the system on the ISS but it's close.

https://esahubble.org/about/general/soft_capture/

Dragon's primary thrusters are actually in its nose. The biggest engines on Dragon aren't used; they've been relegated to the abort system - so the engine nacelles you see around the perimeter of the capsule are essentially nonfunctional.

Becuase Dragon has a nose cap that would interfere with using the docking adapter on Hubble, what will probably have to be done is for a different docking system to be built inside the service module behind the heatshield. Then Dragon would "back up" to dock with Hubble.

Dragon is capable of spacewalks - the first will happen soon as a part of a private spaceflight mission. Astronauts would exit Dragon and navigate to Hubble to perform work on it in this scenario.

There won't be a robotic arm, barring some really exotic offers from Canada.