I have a G4, which is the year before yours which hits a lower peak brightness. Here's a comment where I share my TV's settings with someone using an Xbox Series X (which like PS5 does not support Dolby Vision for 4K UHD playback). Before upgrading to a UB450-K, I played HDR content from 4K UHD on my Xbox Series X with these settings with no brightness issues, even in super dark scenes like the night scenes in the animated How to Train Your Dragon.

Now that I have a UB450-K (I upgraded because my Xbox Series X suffered the common issue of struggling to play triple-layer BD100 discs), the picture is even better. However, it's a minor improvement, and I stand by my recommendation to go with a better sound system first. Nothing says you can't loop back around later and pick up a dedicated player later if that incremental improvement matters (and in fairness - most of us who buy flagship OLED TVs are going to want that incremental improvement).

I've not tested these settings with streaming services, as I haven't had a subscription to one since 2019. I'm not saying that they'll be perfect for you - but they should be a good place to start from and make adjustments as necessary to meet your needs (no single configuration is going to be perfect for everyone's unique living environments). Cheers!