What FPS will I get in Portal 2 at 1440p?

At 1440p Ultra native, expect around 180 FPS. With DLSS Quality you can push higher.

Does GeForce RTX 5090 SUPRIM SOC support DLSS or FSR in Portal 2?

Portal 2 does not currently support upscalers.

Yes — the GeForce RTX 5090 SUPRIM SOC runs Portal 2 at approximately 240 FPS at 1080p Ultra (native, no upscaling).

✓Yes — Excellent

Expected: 240 FPS @ 1080p Ultra (native).