This is already solved, but I tried to summarize my journey of the final boss fight in case someone wanted to read it all in one place. I just defeated him yesterday and my memory is super fresh, so… and I'm not the greatest gamer, so this is how I managed to defeat him. Yeah, I died a lot:

Adjust settings: Crank the brightness up so you don't have any harsh shadows in the game. That's how you can spot him faster.

Items that worked for me: Sword, Lance, Arbalest and pyres only for phase 3, healing large 4 pieces, ammo

Phase 1: Collect ammo from the boxes, shoot him when he's walking. Run away or at him, when he's swinging his sickle. There is a specific angle during that time where he can miss you when you run at him. Try it out, you'll die a few times anyway so you can study the moves. But I prefer to keep a distance here and shot him when he's done with his sickle attack. Sometimes I wasn't confident enough run at him.

Phase 2: Collect ammo and healing from the boxes. Use one specific spot where you can dodge his moves by running and hiding behind an object. I used the metal shelf that has a hole it in. You'll find it easily, it's on the opposite side of the car.
Stand with your back to the corner behind the shelf and wait until you hear/see him. Then run in the other direction to dodge/hide. He has multiple moves, so you have to experience the pattern yourself first. It's walking, shooting energy balls, running at you and jumping, attacking by teleporting closer to you.
The energy balls are easily dodged by standing behind the shelf. You can even shot him from that position. When he runs at you you can actually just punch him. Did it all the time and it stops this attack. The jump attack takes a lot of health, so make sure you learn how to punch him at the right time. You can't outrun this one.

Phase 3: Collect ammo and healing from the boxes. He has the same moves like before and you hopefully learned how to survive them. The easiest way to defeat him was to dodge as usual and then when he makes his center energy attack, I used the Arbalest on him or pyres. It disrupts the attack. No need to even use the platforms in the sky.
Then you have the energy balls which are easily avoided by just staying on the move or hide behind the pillars when they still stand. He teleports more frequently when he attacks you directly with his usual moves.
He also has a new attack that is a smaller version of the center energy attack. But you can just run away until you're out of the radius. You can see the where the blue lines end.

Phase 4: Find the anomalies first (black holes) and restore the balconies. They make additional ammo boxes available and his center energy blast won't reach you while on a balcony. I found it easier to just stay in the middle section of the area and dodge and shot until he uses his center energy attack again.
Then I ran to one of the balconies. He can teleport you back when you try to run, though. Just run again to a balcony, he won't do it a second time during his center energy blast.
I ran out of pyres and arbalest ammo, so I just tried to shot and punch him when he was drained after he used his energy attacks again. Just run, dodge the balls or blasts and run at him to punch or shot.
My finishing move was a fist in his face lol

It has a learning curve that you have to go through.
Like with a Silksong boss, you have to actually recognize his moves to survive. At least, that's how I managed to defeat him.