From what I can tell from the sample, the Korranberg Psion uses the Wizard spell point system in the Dungeon Master Guide, except Korranberg has many more points than the Wizard at high levels. The difference is because the spell point costs of the Korranberg are the same as the 3e Psion. It differs notably from the 5e costs in the DMG.
I'd take inspiration off psionic monsters. We're talking mind flayer mass stun, etc.. This would include a point system to augment existing 1/rest (long or short) abilities. These abilities should be for augmenting one's body, manipulating minds, or short-distance affect (e.g. like misty step or a short-distance disintegrate).
Certain monster features work well as a psionic spell. You mention the mindflayer mass stun feature. I am also thinking the "Wings" of many races and monsters, unlike "Fly", needs to be a slot-2 spell. The Shapeshifter Psion would be awesome when gaining access to sprouting wings.
Spells have a "At Higher Levels" entry, where players can augment the spell by upcasting it.
A spell point system can be "a point system to augment". That doesnt really relate to how monster features work. But there is a camp who wants to make the psionic power source a silo for experimental mechanics. That is why there needs to be two separate Psion classes. One class is for fans who like psionic flavor and dont want to deal with redundant mechanics that do the same thing that the official mechanics already do. The other class is for fans who like experimental mechanics.
What cancels psions? Wizards know their foes probably get a save. Fighters know they need to hit a target AC. Psions?
Saving throws cancel Psions. Same as all of the other spellcasting classes.
Heh, you mention Wizard versus Fighter, ... but seem to omit ... Wizard, Sorcerer, Bard, Druid, Cleric, and Warlock ... plus Ranger, Paladin, Trickster, Eldritch Knight, and others. They all know their foes probably get a save.
If you're going to use existing spells, spell points, or variations on spells, you're not really creating a new class. A new class stands alone. ... In design, a Psion needs to occupy a niche that no one else does.
Many 5e classes are somewhat redundant with each other.
Conceivably, the Fighter class can include Barbarian, Ranger, and Paladin, similar to the way it includes Samurai, Eldritch Knight, and Psi Warrior. Rogue can probably handle Monk. Apparently, enough players wanted Barbarian, Ranger, Paladin, and Monk to be separate classes.
What matters is, there is a desire for the class. Or conversely, there is frustration when preexisting classes fail to satisfactorily represent all of the various archetypes, mechanics, and narratives relating to a character concept.
Compare the Artificer. It could have been a Wizard, but Artificer fans were unsatisfied with that approach.