I have no experience with breaking any "jailed" systems. I collect lots of normal PC hardware (not jailed) and use only it for everything

In most Linux systems, in the login screen there is a menu where you choose to what desktop to log in

I also wonder if I could break a macbook, a play station or any computer stuck with a jail system. I want to converter my PS2 into a media center and for run software freely, and getting rid of DRMs and jails.

google stuff like "unlock macbook" install linux (also try replacing 'unlock' with 'jailbreak')
Be very cautious of any sites you go to!
Don't use Internet-Explorer or Edge! (infact I only recommend using PaleMoon (or 2nd choice FireFox), and very importantly installing the NoScript addon)
Avoid all sites that are not a .com .org or .net domain!

Oh and most important of all, any site that wants you to download something to unlock: Don't Do It!

google stuff like "unlock macbook" install linux (also try replacing 'unlock' with 'jailbreak')
Be very cautious of any sites you go to!
Don't use Internet-Explorer or Edge! (infact I only recommend using PaleMoon (or 2nd choice FireFox), and very importantly installing the NoScript addon)
Avoid all sites that are not a .com .org or .net domain!

Oh and most important of all, any site that wants you to download something to unlock: Don't Do It!

I'm looking at YouTube tutorials for do that, I'm not gonna open any dodgy site in my main devices around.

If I damage the PS2 following a YT tutorial there's no problem, because I don't care much about that PS2.

Because the console seems to only have RAM and ROM memory, I'll need to run linux from live USB and storing the data there, but first I'll need to "hack" or "crack" the PS2 to boot from the usb memory, then the basic hardware drivers need to be installed, like the video output, the ethernet connection and the optic CD reader.

I found a very trustworthy YT tutorial, I'll try to install linux on the ps2 and then I'll share the results to you.

I wonder if the ps2 computing capacity is enough to play an NTSC DVD quality mpeg video preloaded in an USB memory.

I installed the LXQT desktop in linux mint, and it's running very smoothly, all is perfectly working without lag. The YouTube videos are still a bit laggy but watchable, so I'll leave that distro with that desktop on the computer. Thanks for your help!