Massive player character power disparity and how to deal with it as GM new to the system?
So, I'm playing a Empire Era/dawn of rebellion age campaign with 4 players. Two of them are playing minmaxed monstrosities. One is narratively useful. Last player though, I can see feels a bit left out and dejected, which is not my intention, but I don't know how to deal with. I gave everyone two bonus talents which probably contributes to the issue, allowing for more synergy.
Character 1 is minmaxed Padawan with effectively +19 Use the Force at lvl 4 (20 Cha, Skill Focus and Manifest Spirit Guardian /w Force Harmony). This abomination is ragdolling anything I throw in his way (up to and including Darth Vader, though he wisely had the sense to bolt right after, leading to a Fallen Order-esque escape sequence), and unhurtable due to the talents that allow to stop attacks with saber.
Character 2 is "condition track killer" build, stacking lots of talents that automatically remove conditions. Dastardly Strike, Debilitating Shot, Hunter's Mark. And the thing that gives a droid extra Swift action. It's a mouthy droid that has personality between Han Solo and Hk-47
Character 3 isn't completely stacked for combat but she's a princess, so she's stacked with wealth and connections. (She is on the run since Empire staged a coup on her planet so she cannot just get the army for the job but she is still insanely rich). She's basically who gets the above two loaded with every gadget in the books, and who solves tons of social challenges.
Character 4 has rather uncohesive build. He wants to use a lightsaber but does not want to be Force Sensitive so he cannot actually build any synergy into that. He lacks any mobility and isn't trained in init which more often than not means that Character 1 and 2 have blown the opposition to smithereens before he gets to melee.
The situation isn't helped the three first players are confident and bantering, joking, flirting as their characters all the time. The fourth is shy.
This is awkward to me as the GM. I do not want to force anyone to build a certain way, nor to tell they need to speak more. But I also don't want anyone to be left out and I feel like one of my players is, even if nobody is excluding him on purpose.
Should I just sit down with him and remake his build talent by talent to create something that can get things done at same rate as the others?
Or should I give him extra levels to compensate?
Or should I try to make story elements related to him (Mandalorians) more relevant to the story to nudge him towards being the party lead for some time?